seven-transmembrane G protein-coupled receptor superfamily; This hierarchical evolutionary model represents the seven-transmembrane (7TM) receptors, often referred to as G protein-coupled receptors (GPCRs), which transmit physiological signals from the outside of the cell to the inside via G proteins. GPCRs constitute the largest known superfamily of transmembrane receptors across the three kingdoms of life that respond to a wide variety of extracellular stimuli including peptides, lipids, neurotransmitters, amino acids, hormones, and sensory stimuli such as light, smell and taste. All GPCRs share a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes. However, some 7TM receptors, such as the type 1 microbial rhodopsins, do not activate G proteins. Based on sequence similarity, GPCRs can be divided into six major classes: class A (the rhodopsin-like family), class B (the Methuselah-like, adhesion and secretin-like receptor family), class C (the metabotropic glutamate receptor family), class D (the fungal mating pheromone receptors), class E (the cAMP receptor family), and class F (the frizzled/smoothened receptor family). Nearly 800 human GPCR genes have been identified and are involved essentially in all major physiological processes. Approximately 40% of clinically marketed drugs mediate their effects through modulation of GPCR function for the treatment of a variety of human diseases including bacterial infections.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897 576 LTNFAILMQVVP----LEVNIGILIAVTRVISQISADNYKIHGDPSAFKLTAKAVAVLLPILGTSWVFGVLAVNGCAVVF 651
Cdd:cd15256  146 LENGAIWAFVAPalfvIVVNIGILIAVTRVISRISADNYKVHGDANAFKLTAKAVAVLLPILGSSWVFGVLAVNTHALVF 225

                         90       100       110
                 ....*....|....*....|....*....|....*
gi 767973897 652 QYMFATLNSLQGLFIFLFHCLLNSEVRAAFKHKTK 686
Cdd:cd15256  226 QYMFAIFNSLQGFFIFLFHCLLNSEVRAAFKHKTK 260

Concanavalin A-like lectin/glucanases superfamily; This domain belongs to the Concanavalin A-like lectin/glucanases superfamily.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897  170 SSGGRGSVELYTRDNSM-TWEASFSPPGPYWTHVLFTWkSKEGLKVYVNGTL--STSDPSGKVSRDYGesnvNLVIGSEQ 246
Cdd:pfam13385  51 DGDGRLRFAVNGGNGGWdTVTSGASVPLGQWTHVAVTY-DGGTLRLYVNGVLvgSSTLTGGPPPGTGG----PLYIGRSP 125

                          90       100
                  ....*....|....*....|....*..
gi 767973897  247 DqAKCYENGAFDEFIIWERALTPDEIA 273
Cdd:pfam13385 126 G-GDDYFNGLIDEVRIYDRALSAAEIA 151

orphan adhesion receptor GPR133, member of the class B2 family of seven-transmembrane G protein-coupled receptors; GPR133 is an orphan receptor that belongs to the group V adhesion-GPCRs together with GPR144. The function of GPR144 has not yet been characterized, whereas GPR133 is highly expressed in the pituitary gland and is coupled to the Gs protein, leading to activation of adenylyl cyclase pathway. Moreover, genetic variations in the GPR133 have been reported to be associated with adult height and heart rate. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in ligand recognition as well as cell-cell adhesion and cell-matrix interactions, linked by a stalk region to a class B seven-transmembrane domain. In addition, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions. However, several adhesion GPCRs, including GPR 111, GPR115, and CELSR1, are predicted to be non-cleavable at the GAIN domain because of the lack of a consensus catalytic triad sequence (His-Leu-Ser/Thr) within their GPS.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897 576 LTNFAILMQVVP----LEVNIGILIAVTRVISQISADNYKIHGDPSAFKLTAKAVAVLLPILGTSWVFGVLAVNGCAVVF 651
Cdd:cd15256  146 LENGAIWAFVAPalfvIVVNIGILIAVTRVISRISADNYKVHGDANAFKLTAKAVAVLLPILGSSWVFGVLAVNTHALVF 225

                         90       100       110
                 ....*....|....*....|....*....|....*
gi 767973897 652 QYMFATLNSLQGLFIFLFHCLLNSEVRAAFKHKTK 686
Cdd:cd15256  226 QYMFAIFNSLQGFFIFLFHCLLNSEVRAAFKHKTK 260

G-protein-coupled receptor proteolytic site domain; Present in latrophilin/CL-1, sea urchin REJ and polycystin.

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|....*...
gi 767973897   540 VYCAFldFSSGEGVWSNHGCALTRGNLTYSVCRCTHLTNFAILMQVVP 587
Cdd:smart00303   3 PICVF--WDESSGEWSTRGCELLETNGTHTTCSCNHLTTFAVLMDVPP 48

7 transmembrane receptor (Secretin family); This family is known as Family B, the secretin-receptor family or family 2 of the G-protein-coupled receptors (GCPRs). They have been described in many animal species, but not in plants, fungi or prokaryotes. Three distinct sub-families are recognized. Subfamily B1 contains classical hormone receptors, such as receptors for secretin and glucagon, that are all involved in cAMP-mediated signalling pathways. Subfamily B2 contains receptors with long extracellular N-termini, such as the leukocyte cell-surface antigen CD97; calcium-independent receptors for latrotoxin, and brain-specific angiogenesis inhibitors amongst others. Subfamily B3 includes Methuselah and other Drosophila proteins. Other than the typical seven-transmembrane region, characteriztic structural features include an amino-terminal extracellular domain involved in ligand binding, and an intracellular loop (IC3) required for specific G-protein coupling.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897  590 VNIGILIAVTRVISQISADNYKIHGDPSAFKLTAKAVAVLLPILGTSWVFGVLAVN---GCAVVFQYMFATLNSLQGLFI 666
Cdd:pfam00002 169 VNFIIFINIVRILVQKLRETNMGKSDLKQYRRLAKSTLLLLPLLGITWVFGLFAFNpenTLRVVFLYLFLILNSFQGFFV 248

Pentraxin / C-reactive protein / pentaxin family; This family form a doscoid pentameric structure. Human serum amyloid P demonstrates calcium-mediated ligand-binding.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897   175 GSVELYTRDNSMTWEASFSPPGpyWTHVLFTWKSKEGL-KVYVNGTLSTsdpsGKVS-RDYG-ESNVNLVIGSEQDqakC 251
Cdd:smart00159  70 GEYSLYIGGKKVQFPVPESDGK--WHHICTTWESSSGIaELWVDGKPGV----RKGLaKGYTvKPGGSIILGQEQD---S 140

                           90       100       110
                   ....*....|....*....|....*....|....*...
gi 767973897   252 YeNGAFD----------EFIIWERALTPDEIAMYFTAA 279
Cdd:smart00159 141 Y-GGGFDatqsfvgeigDLNMWDSVLSPEEIKSVYKGS 177

orphan adhesion receptor GPR133, member of the class B2 family of seven-transmembrane G protein-coupled receptors; GPR133 is an orphan receptor that belongs to the group V adhesion-GPCRs together with GPR144. The function of GPR144 has not yet been characterized, whereas GPR133 is highly expressed in the pituitary gland and is coupled to the Gs protein, leading to activation of adenylyl cyclase pathway. Moreover, genetic variations in the GPR133 have been reported to be associated with adult height and heart rate. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in ligand recognition as well as cell-cell adhesion and cell-matrix interactions, linked by a stalk region to a class B seven-transmembrane domain. In addition, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions. However, several adhesion GPCRs, including GPR 111, GPR115, and CELSR1, are predicted to be non-cleavable at the GAIN domain because of the lack of a consensus catalytic triad sequence (His-Leu-Ser/Thr) within their GPS.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897 576 LTNFAILMQVVP----LEVNIGILIAVTRVISQISADNYKIHGDPSAFKLTAKAVAVLLPILGTSWVFGVLAVNGCAVVF 651
Cdd:cd15256  146 LENGAIWAFVAPalfvIVVNIGILIAVTRVISRISADNYKVHGDANAFKLTAKAVAVLLPILGSSWVFGVLAVNTHALVF 225

                         90       100       110
                 ....*....|....*....|....*....|....*
gi 767973897 652 QYMFATLNSLQGLFIFLFHCLLNSEVRAAFKHKTK 686
Cdd:cd15256  226 QYMFAIFNSLQGFFIFLFHCLLNSEVRAAFKHKTK 260

adhesion receptors, subfamily B2 of the class B family of seven-transmembrane G protein-coupled receptors; The B2 subfamily of class B GPCRs consists of cell-adhesion receptors with 33 members in humans and vertebrates. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing a variety of structural motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, linked to a class B seven-transmembrane domain. These include, for example, EGF (epidermal growth factor)-like domains in CD97, Celsr1 (cadherin family member), Celsr2, Celsr3, EMR1 (EGF-module-containing mucin-like hormone receptor-like 1), EMR2, EMR3, and Flamingo; two laminin A G-type repeats and nine cadherin domains in Flamingo and its human orthologs Celsr1, Celsr2 and Celsr3; olfactomedin-like domains in the latrotoxin receptors; and five or four thrombospondin type 1 repeats in BAI1 (brain-specific angiogenesis inhibitor 1), BAI2 and BAI3. Furthermore, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR- autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897 590 VNIGILIAVTRVISQISADNYKihGDPSAFKLTAKAVAVLLPILGTSWVFGVLAVNGCAVVFQYMFATLNSLQGLFIFLF 669
Cdd:cd15040  164 VNLVIFVLVLRKLLRLSAKRNK--KKRKKTKAQLRAAVSLFFLLGLTWIFGILAIFGARVVFQYLFAIFNSLQGFFIFIF 241

                         90
                 ....*....|..
gi 767973897 670 HCLLNSEVRAAF 681
Cdd:cd15040  242 HCLRNKEVRKAW 253

invertebrate latrophilin-like receptors, member of the class B2 family of seven-transmembrane G protein-coupled receptors; This subgroup includes latrophilin-like proteins that are found in invertebrates such as insects and worms. Latrophilins (also called lectomedins or latrotoxin receptors) belong to Group I adhesion GPCRs, which also include ETL (EGF-TM7-latrophilin-related protein). These receptors are a member of the adhesion family (subclass B2) that belongs to the class B GPCRs. Three subtypes of vertebrate latrophilins have been identified: LPH1 (latrophilin-1), LPH2, and LPH3. The latrophilin-1 is a brain-specific calcium-independent receptor of alpha-latrotoxin, a potent presynaptic neurotoxin from the venom of the black widow spider that induces massive neurotransmitter release from sensory and motor neurons as well as endocrine cells, leading to nerve-terminal degeneration. Latrophilin-2 and -3, although sharing strong sequence homology to latrophilin-1, do not bind alpha-latrotoxin. While latrophilin-3 is also brain specific, latrophilin-2 is ubiquitously distributed. The endogenous ligands for these two receptors are unknown. ETL, a seven transmembrane receptor containing EGF-like repeats is highly expressed in heart, where developmentally regulated, as well as in normal smooth cells. The function of the ETL is unknown. All adhesion GPCRs possess large N-terminal extracellular domains containing multiple structural motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, coupled to a seven-transmembrane domain. In addition, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897 579 FAILMQVVPLEVNIGILIAVTRVISQIsadnyKIHGDPSAFKLTAKAVAVLLPILGTSWVFGVLAVNGCAVVFQYMFATL 658
Cdd:cd15440  157 VVLLANLVFLGMAIYVMCRHSSRSASK-----KDASKLKNIRGWLKGSIVLVVLLGLTWTFGLLFINQESIVMAYIFTIL 231

                         90       100
                 ....*....|....*....|
gi 767973897 659 NSLQGLFIFLFHCLLNSEVR 678
Cdd:cd15440  232 NSLQGLFIFIFHCVLNEKVR 251

orphan GPR116 and related proteins, group IV adhesion GPCRs, member of the class B2 family of seven-transmembrane G protein-coupled receptors; group VI adhesion GPCRs consist of orphan receptors GPR110, GPR111, GPR113, GPR115, GPR116, and closely related proteins. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in ligand recognition as well as cell-cell adhesion and cell-matrix interactions, linked by a stalk region to a class B seven-transmembrane domain. GPR110 possesses a SEA box in the N-terminal has been identified as an oncogene over-expressed in lung and prostate cancer. GPR113 contains a hormone binding domain and one EGF (epidermal grown factor) domain. GPR112 has extremely long N-terminus (about 2,400 amino acids) containing a number of Ser/Thr-rich glycosylation sites and a pentraxin (PTX) domain. GPR116 has two C2-set immunoglobulin-like repeats, which is found in the members of the immunoglobulin superfamily of cell surface proteins, and a SEA (sea urchin sperm protein, enterokinase, and a grin)-box, which is present in the extracellular domain of the transmembrane mucin (MUC) family and known to enhance O-glycosylation. In addition, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions. However, several adhesion GPCRs, including GPR 111, GPR115, and CELSR1, are predicted to be non-cleavable at the GAIN domain because of the lack of a consensus catalytic triad sequence (His-Leu-Ser/Thr) within their GPS.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897 560 ALTRGNLTYS---VCRCTHLTNFAILMQVVP----LEVNIGILIAVTRVISQISADNYKIHGDPSAFKLTAKAVAVLLPI 632
Cdd:cd15932  138 AATAPQGGYTrkgVCWLNWDKTKALLAFVIPalaiVVVNFIILIVVIFKLLRPSVGERPSKDEKNALVQIGKSVAILTPL 217

                         90       100       110       120       130
                 ....*....|....*....|....*....|....*....|....*....|.
gi 767973897 633 LGTSWVFGV-LAVNGCAVVFQYMFATLNSLQGLFIFLFHCLLNSEVRAAFK 682
Cdd:cd15932  218 LGLTWGFGLgTMIDPKSLAFHIIFAILNSFQGFFILVFGTLLDSKVREALL 268

EGF-like module receptors, group II adhesion GPCRs, member of class B2 family of seven-transmembrane G protein-coupled receptors; group II adhesion GPCRs, including the leukocyte cell-surface antigen CD97 and the epidermal growth factor (EGF)-module-containing, mucin-like hormone receptor (EMR1-4), are primarily expressed in cells of the immune system. All EGF-TM7 receptors, which belong to the B2 subfamily B2 of adhesion GPCRs, are members of group II, except for ETL (EGF-TM7-latrophilin related protein), which is classified into group I. Members of the EGF-TM7 receptors are characterized by the presence of varying numbers of N-terminal EGF-like domains, which play critical roles in ligand recognition and cell adhesion, linked by a stalk region to a class B seven-transmembrane domain. In the case of CD97, alternative splicing results in three isoforms possessing either three (EGF1,2,5), four (EGF1,2,3,5) or five (EGF1,2,3,4,5) EGF-like domains. On the other hand, EMR2 generates four isoforms possessing either two (EGF1,2), three (EGF1,2,5), four (EGF1,2,3,5) or five (EGF1,2,3,4,5) EGF-like domains. Moreover, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR- autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions. For example, CD97, which is involved in angiogenesis and the migration and invasion of tumor cells, has been shown to promote cell aggregation in a GPS proteolysis-dependent manner. CD97 is widely expressed on lymphocytes, monocytes, macrophages, dendritic cells, granulocytes and smooth muscle cells as well as in a variety of human tumors including colorectal, gastric, esophageal pancreatic, and thyroid carcinoma. EMR2 shares strong sequence homology with CD97, differing by only six amino acids. However, unlike CD97, EMR2 is not found in those of CD97-positive tumor cells and is not expressed on lymphocytes but instead on monocytes, macrophages and granulocytes. CD97 has three known ligands: CD55, decay-accelerating factor for regulation of complement system; chondroitin sulfate, a glycosaminoglycan found in the extracellular matrix; and the integrin alpha5beta1, which play a role in angiogenesis. Although EMR2 does not effectively interact with CD55, the fourth EGF-like domain of this receptor binds to chondroitin sulfate to mediate cell attachment.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|..
gi 767973897 621 LTAKAVAVLLpILGTSWVFGVLAVNGCAVVFQYMFATLNSLQGLFIFLFHCLLNSEVRAAFK 682
Cdd:cd15931  198 LTFKAVAQLF-ILGCTWVLGLFQTNPVALVFQYLFTILNSLQGAFLFLVHCLLNKEVREEYI 258

CD97 antigen, member of the class B2 family of seven-transmembrane G protein-coupled receptors; group II adhesion GPCRs, including the leukocyte cell-surface antigen CD97 and the epidermal growth factor (EGF)-module-containing, mucin-like hormone receptor (EMR1-4), are primarily expressed in cells of the immune system. All EGF-TM7 receptors, which belong to the B2 subfamily B2 of adhesion GPCRs, are members of group II, except for ETL (EGF-TM7-latrophilin related protein), which is classified into group I. Members of the EGF-TM7 receptors are characterized by the presence of varying numbers of N-terminal EGF-like domains, which play critical roles in ligand recognition and cell adhesion, linked by a stalk region to a class B seven-transmembrane domain. In the case of CD97, alternative splicing results in three isoforms possessing either three (EGF1,2,5), four (EGF1,2,3,5) or five (EGF1,2,3,4,5) EGF-like domains. Moreover, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR- autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions. For example, CD97, which is involved in angiogenesis and the migration and invasion of tumor cells, has been shown to promote cell aggregation in a GPS proteolysis-dependent manner. CD97 is widely expressed on lymphocytes, monocytes, macrophages, dendritic cells, granulocytes and smooth muscle cells as well as in a variety of human tumors including colorectal, gastric, esophageal pancreatic, and thyroid carcinoma. EMR2 shares strong sequence homology with CD97, differing by only six amino acids. However, unlike CD97, EMR2 is not found in those of CD97-positive tumor cells and is not expressed on lymphocytes but instead on monocytes, macrophages and granulocytes. CD97 has three known ligands: CD55, decay-accelerating factor for regulation of complement system; chondroitin sulfate, a glycosaminoglycan found in the extracellular matrix; and the integrin alpha5beta1, which play a role in angiogenesis. Although EMR2 does not effectively interact with CD55, the fourth EGF-like domain of this receptor binds to chondroitin sulfate to mediate cell attachment.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 767973897 621 LTAKAVAVLLpILGTSWVFGVLAVNGCAVVFQYMFATLNSLQGLFIFLFHCLLNSEVRAAF 681
Cdd:cd15438  193 LTITAIAQLC-ILGCTWIFGFFQFSDSTLVMSYLFTILNSLQGLFIFLLHCLLSKQVREEY 252

GPCR proteolysis site, GPS, motif; The GPS motif is found in GPCRs, and is the site for auto-proteolysis, so is thus named, GPS. The GPS motif is a conserved sequence of ~40 amino acids containing canonical cysteine and tryptophan residues, and is the most highly conserved part of the domain. In most, if not all, cell-adhesion GPCRs these undergo autoproteolysis in the GPS between a conserved aliphatic residue (usually a leucine) and a threonine, serine, or cysteine residue. In higher eukaryotes this motif is found embedded in the C-terminal beta-stranded part of a GAIN domain - GPCR-Autoproteolysis INducing (GAIN). The GAIN-GPS domain adopts a fold in which the GPS motif, at the C-terminus, forms five beta-strands that are tightly integrated into the overall GAIN domain. The GPS motif, evolutionarily conserved from tetrahymena to mammals, is the only extracellular domain shared by all human cell-adhesion GPCRs and PKD proteins, and is the locus of multiple human disease mutations. The GAIN-GPS domain is both necessary and sufficient functionally for autoproteolysis, suggesting an autoproteolytic mechanism whereby the overall GAIN domain fine-tunes the chemical environment in the GPS to catalyze peptide bond hydrolysis. In the cell-adhesion GPCRs and PKD proteins, the GPS motif is always located at the end of their long N-terminal extracellular regions, immediately before the first transmembrane helix of the respective protein.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|..
gi 767973897  542 CAFLDFS-SGEGVWSNHGCALTRGNLTYSVCRCTHLTNFAIL 582
Cdd:pfam01825   3 CVFWDFTnSTTGRWSTEGCTTVSLNDTHTVCSCNHLTSFAVL 44

Concanavalin A-like lectin/glucanases superfamily; This domain belongs to the Concanavalin A-like lectin/glucanases superfamily.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897  170 SSGGRGSVELYTRDNSM-TWEASFSPPGPYWTHVLFTWkSKEGLKVYVNGTL--STSDPSGKVSRDYGesnvNLVIGSEQ 246
Cdd:pfam13385  51 DGDGRLRFAVNGGNGGWdTVTSGASVPLGQWTHVAVTY-DGGTLRLYVNGVLvgSSTLTGGPPPGTGG----PLYIGRSP 125

                          90       100
                  ....*....|....*....|....*..
gi 767973897  247 DqAKCYENGAFDEFIIWERALTPDEIA 273
Cdd:pfam13385 126 G-GDDYFNGLIDEVRIYDRALSAAEIA 151

7 transmembrane receptor (Secretin family); This family is known as Family B, the secretin-receptor family or family 2 of the G-protein-coupled receptors (GCPRs). They have been described in many animal species, but not in plants, fungi or prokaryotes. Three distinct sub-families are recognized. Subfamily B1 contains classical hormone receptors, such as receptors for secretin and glucagon, that are all involved in cAMP-mediated signalling pathways. Subfamily B2 contains receptors with long extracellular N-termini, such as the leukocyte cell-surface antigen CD97; calcium-independent receptors for latrotoxin, and brain-specific angiogenesis inhibitors amongst others. Subfamily B3 includes Methuselah and other Drosophila proteins. Other than the typical seven-transmembrane region, characteriztic structural features include an amino-terminal extracellular domain involved in ligand binding, and an intracellular loop (IC3) required for specific G-protein coupling.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897  590 VNIGILIAVTRVISQISADNYKIHGDPSAFKLTAKAVAVLLPILGTSWVFGVLAVN---GCAVVFQYMFATLNSLQGLFI 666
Cdd:pfam00002 169 VNFIIFINIVRILVQKLRETNMGKSDLKQYRRLAKSTLLLLPLLGITWVFGLFAFNpenTLRVVFLYLFLILNSFQGFFV 248

Latrophilin-2, member of the class B2 family of seven-transmembrane G protein-coupled receptors; Latrophilins (also called lectomedins or latrotoxin receptors) belong to Group I adhesion GPCRs, which also include ETL (EGF-TM7-latrophilin-related protein). These receptors are a member of the adhesion family (subclass B2) that belongs to the class B GPCRs. Three subtypes of latrophilins have been identified: LPH1 (latrophilin-1), LPH2, and LPH3. The latrophilin-1 is a brain-specific calcium-independent receptor of alpha-latrotoxin, a potent presynaptic neurotoxin from the venom of the black widow spider that induces massive neurotransmitter release from sensory and motor neurons as well as endocrine cells, leading to nerve-terminal degeneration. Latrophilin-2 and -3, although sharing strong sequence homology to latrophilin-1, do not bind alpha-latrotoxin. While latrophilin-3 is also brain specific, latrophilin-2 is ubiquitously distributed. The endogenous ligands for these two receptors are unknown. ETL, a seven transmembrane receptor containing EGF-like repeats is highly expressed in heart, where developmentally regulated, as well as in normal smooth cells. The function of the ETL is unknown. All adhesion GPCRs possess large N-terminal extracellular domains containing multiple structural motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, coupled to a seven-transmembrane domain. In addition, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....
gi 767973897 628 VLLPILGTSWVFGVLAVNGCAVVFQYMFATLNSLQGLFIFLFHCLLNSEVRAAF 681
Cdd:cd16006  199 ALLCLLGLTWSFGLLFINEETIVMAYLFTIFNAFQGMFIFIFHCALQKKVRKEY 252

The immunoglobulin-repeat-containing receptor Ig-hepta/GPR116, member of the class B2 family of seven-transmembrane G protein-coupled receptors; GPR116 (also known as Ig-hepta) is an orphan receptor that belongs to group VI adhesion-GPCRs along with GPR110, GPR111, GPR113, and GPR115. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in ligand recognition as well as cell-cell adhesion and cell-matrix interactions, linked by a stalk region to a class B seven-transmembrane domain. GPR116 has four I-set immunoglobulin-like repeats, which is found in the members of the immunoglobulin superfamily of cell surface proteins, and a SEA (sea urchin sperm protein, enterokinase, and a grin)-box, which is present in the extracellular domain of the transmembrane mucin (MUC) family and known to enhance O-glycosylation. GPR116 is highly expressed in fetal and adult lung, and it has been shown to regulate lung surfactant levels as well as to stimulate breast cancer metastasis through a G(q)-p63-RhoGEF-Rho GTPase signaling pathway. In addition, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions. However, several adhesion GPCRs, including GPR 111, GPR115, and CELSR1, are predicted to be non-cleavable at the GAIN domain because of the lack of a consensus catalytic triad sequence (His-Leu-Ser/Thr) within their GPS.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897 580 AILMQVVP----LEVNIGILIAVTRVISQISADNYKIHGDPSAFKLTAKAVAVLLPILGTSWVFGVLAV-NGCAVVFQYM 654
Cdd:cd15254  163 ALLAFVIPaliiVAVNSIITVVVIVKILRPSIGEKPSKQERSSLFQIIKSIGVLTPLLGLTWGFGLATViKGSSIVFHIL 242

                         90       100       110
                 ....*....|....*....|....*....|
gi 767973897 655 FATLNSLQGLFIFLFHCLLNSEVRAAFKHK 684
Cdd:cd15254  243 FTLLNAFQGLFILVFGTLWDKKVQEALLNK 272

Latrophilin-3, member of the class B2 family of seven-transmembrane G protein-coupled receptors; Latrophilins (also called lectomedins or latrotoxin receptors) belong to Group I adhesion GPCRs, which also include ETL (EGF-TM7-latrophilin-related protein). These receptors are a member of the adhesion family (subclass B2) that belongs to the class B GPCRs. Three subtypes of latrophilins have been identified: LPH1 (latrophilin-1), LPH2, and LPH3. The latrophilin-1 is a brain-specific calcium-independent receptor of alpha-latrotoxin, a potent presynaptic neurotoxin from the venom of the black widow spider that induces massive neurotransmitter release from sensory and motor neurons as well as endocrine cells, leading to nerve-terminal degeneration. Latrophilin-2 and -3, although sharing strong sequence homology to latrophilin-1, do not bind alpha-latrotoxin. While latrophilin-3 is also brain specific, latrophilin-2 is ubiquitously distributed. The endogenous ligands for these two receptors are unknown. ETL, a seven transmembrane receptor containing EGF-like repeats is highly expressed in heart, where developmentally regulated, as well as in normal smooth cells. The function of the ETL is unknown. All adhesion GPCRs possess large N-terminal extracellular domains containing multiple structural motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, coupled to a seven-transmembrane domain. In addition, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 767973897 629 LLPILGTSWVFGVLAVNGCAVVFQYMFATLNSLQGLFIFLFHCLLNSEVRAAF 681
Cdd:cd16005  200 LLCLLGLTWAFGLMYINESTVIMAYLFTIFNSLQGMFIFIFHCVLQKKVRKEY 252

orphan adhesion receptor GPR113, member of the class B2 family of seven-transmembrane G protein-coupled receptors; GPR113 is an orphan receptor that belongs to group VI adhesion-GPCRs along with GPR110, GPR111, GPR115, and GPR116. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in ligand recognition as well as cell-cell adhesion and cell-matrix interactions, linked by a stalk region to a class B seven-transmembrane domain. GPR113 contains a hormone binding domain and one EGF (epidermal grown factor) domain, and is primarily expressed in a subset of taste receptor cells. In addition, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions. However, several adhesion GPCRs, including GPR 111, GPR115, and CELSR1, are predicted to be non-cleavable at the GAIN domain because of the lack of a consensus catalytic triad sequence (His-Leu-Ser/Thr) within their GPS.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|..
gi 767973897 624 KAVAVLLPILGTSWVFGVLAVNG-CAVVFQYMFATLNSLQGLFIFLFHCLLNSEVRAAFKHK 684
Cdd:cd15253  207 KALLVLTPVFGLTWGLGVATLTGeSSQVSHYGFAILNAFQGVFILLFGCLMDKKVREALLKR 268

insect diuretic hormone receptors, member of the class B family of seven-transmembrane G protein-coupled receptors; This group includes G protein-coupled receptors that specifically bind to insect diuretic hormones found in Manduca sexta (moth) and Acheta domesticus (the house cricket), among others. Insect diuretic hormone and their GPCRs play critical roles in the regulation of water and ion balance. Thus they are attractive targets for developing new insecticides. Activation of the diuretic hormone receptors stimulate adenylate cyclase, thereby increasing cAMP levels in Malpighian tube. They belong to the B1 subfamily of class B GPCRs, also referred to as secretin-like receptor family, which includes receptors for polypeptide hormones of 27-141 amino-acid residues such as secretin, glucagon, glucagon-like peptide (GLP), calcitonin gene-related peptide, parathyroid hormone (PTH), and corticotropin-releasing factor. These receptors contain the large N-terminal extracellular domain (ECD), which plays a critical role in hormone recognition by binding to the C-terminal portion of the peptide. On the other hand, the N-terminal segment of the hormone induces receptor activation by interacting with the receptor transmembrane domains and connecting extracellular loops, triggering intracellular signaling pathways. All members of the B1 subfamily preferentially couple to G proteins of Gs family, which positively stimulate adenylate cyclase, leading to increased intracellular cAMP formation and calcium influx.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 767973897 623 AKAVAVLLPILGTSWVFgVLAV---NGCAVVFQYMFATLNSLQGLFIFLFHCLLNSEVRAAFKH 683
Cdd:cd15263  206 AKALLVLIPLLGITYIL-VIAGpteGIAANIFEYVRAVLLSTQGFTVALFYCFLNTEVRNTLRH 268

orphan adhesion receptors GPR111 and GPR115, member of the class B2 family of seven-transmembrane G protein-coupled receptors; GPR111 and GPR115 are highly homologous orphan receptors that belong to group VI adhesion-GPCRs along with GPR110, GPR113, and GPR116. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in ligand recognition as well as cell-cell adhesion and cell-matrix interactions, linked by a stalk region to a class B seven-transmembrane domain. In addition, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions. However, several adhesion GPCRs, including GPR 111, GPR115, and CELSR1, are predicted to be non-cleavable at the GAIN domain because of the lack of a consensus catalytic triad sequence (His-Leu-Ser/Thr) within their GPS. Both GPR111 and GPR5 are present only in land-living animals and are predominantly expressed in the developing skin.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897 580 AILMQVVPLEVNIGI-LIAVTRVI--SQISADNYKIHGDPSAFKLTAKAVAVLLPILGTSWVFGVLA-VNGCAVVFQYMF 655
Cdd:cd15994  161 ALLAFIIPALSIVVVnLIVVGVVVvkTQRSSIGESCKQDVSNIIRISKNVAILTPLLGLTWGFGLATiIDSRSLPFHIIF 240

                         90       100
                 ....*....|....*....|....*..
gi 767973897 656 ATLNSLQGLFIFLFHCLLNSEVRAAFK 682
Cdd:cd15994  241 ALLNAFQGFFILLFGTILDRKIRIALY 267

brain-specific angiogenesis inhibitors, group VII adhesion GPCRs, member of the class B2 family of seven-transmembrane G protein-coupled receptors; Brain-specific angiogenesis inhibitors (BAI1-3) constitute the group VII of cell-adhesion receptors that have been implicated in vascularization of glioblastomas. They belong to the B2 subfamily of class B GPCRs, are predominantly expressed in the brain, and are only present in vertebrates. Three BAIs, like all adhesion receptors, are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, that are coupled to a class B seven-transmembrane domain. For example, BAI1 N-terminus contain an integrin-binding RGD (Arg-Gly-Asp) motif in addition to five thrombospondin type 1 repeats (TSRs), which are known to regulate the anti-angiogenic activity of thrombospondin-1, whereas BAI2 and BAI3 have four TSRs, but do not possess RGD motifs. The TSRs are functionally involved in cell attachment, activation of latent TGF-beta, inhibition of angiogenesis and endothelial cell migration. The TSRs of BAI1 mediate direct binding to phosphatidylserine, which enables both recognition and internalization of apoptotic cells by phagocytes. Thus, BAI1 functions as a phosphatidylserine receptor that forms a trimeric complex with ELMO and Dock180, leading to activation of Rac-GTPase which promotes the binding and phagocytosis of apoptotic cells. BAI3 can also interact with the ELMO-Dock180 complex to activate the Rac pathway and can also bind to secreted C1ql proteins of the C1Q complement family via its N-terminal TSRs. BAI3 and its ligands C1QL1 are highly expressed during synaptogenesis and are involved in synapse specificity. Moreover, BAI2 acts as a transcription repressor to regulate vascular endothelial growth factor (VEGF) expression through interaction with GA-binding protein gamma (GABP). The N-terminal extracellular domains of all three BAIs also contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain, which undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif to generate N- and C-terminal fragments (NTF and CTF), a putative hormone-binding domain (HBD), and multiple N-glycosylation sites. The C-terminus of each BAI subtype ends with a conserved Gln-Thr-Glu-Val (QTEV) motif known to interact with PDZ domain-containing proteins, but only BAI1 possesses a proline-rich region, which may be involved in protein-protein interactions.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....*.
gi 767973897 628 VLLPILGTSWVFGVLAV-NGCAVVFQYMFATLNSLQGLFIFLFHCLLNSEVRAAFK 682
Cdd:cd15251  193 VVLPLLALTWMSAVLAMtDRRSVLFQILFAVFDSLQGFVIVMVHCILRREVQDAVK 248

orphan adhesion receptor GPR126, member of the class B2 family of seven-transmembrane G protein-coupled receptors; GPR126 is an orphan receptor that has been classified as that belongs to the Group VIII of adhesion GPCRs. Other members of the Group VII include orphan GPCRs such as GPR56, GPR64, GPR97, GPR112, and GPR114. GPR126 is required in Schwann cells for proper differentiation and myelination via G-Protein Activation. GPR126 is believed to couple to G(s)-protein, which leads to activation of adenylate cyclase for cAMP production. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, that are coupled to a class B seven-transmembrane domain. Furthermore, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR- autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....*....
gi 767973897 624 KAVAVLLPILGTSWVFGVLAVNGCAVVFQYMFATLNSLQGLFIFLFHCLLNSEVRAAFK 682
Cdd:cd15996  210 RSVVSLTFLLGMTWGFAFFAWGPVNLAFMYLFTIFNSLQGLFIFVFHCALKENVQKQWR 268

Cadherin EGF LAG seven-pass G-type receptor 2, member of the class B2 family of seven-transmembrane G protein-coupled receptors; The group IV adhesion GPCRs include the cadherin EGF LAG seven-pass G-type receptors (CELSRs) and their Drosophila homolog Flamingo (also known as Starry night). These receptors are also classified as that belongs to the EGF-TM7 group of subfamily B2 adhesion GPCRs, because they contain EGF-like domains. Functionally, the group IV receptors act as key regulators of many physiological processes such as endocrine cell differentiation, neuronal migration, dendrite growth, axon, guidance, lymphatic vessel and valve formation, and planar cell polarity (PCP) during embryonic development. Three mammalian orthologs of Flamingo, Celsr1-3, are widely expressed in the nervous system from embryonic development until the adult stage. Each Celsr exhibits different expression patterns in the developing brain, suggesting that they serve distinct functions. Mutations of CELSR1 cause neural tube defects in the nervous system, while mutations of CELSR2 are associated with coronary heart disease. Moreover, CELSR1 and several other PCP signaling molecules, such as dishevelled, prickle, frizzled, have been shown to be upregulated in B lymphocytes of chronic lymphocytic leukemia patients. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, that are coupled to a class B seven-transmembrane domain. In the case of CELSR/Flamingo/Starry night, their extracellular domains comprise nine cadherin repeats linked to a series of epidermal growth factor (EGF)-like and laminin globular (G)-like domains. The cadherin repeats contain sequence motifs that mediate calcium-dependent cell-cell adhesion by homophilic interactions. Moreover, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR- autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....*....
gi 767973897 624 KAVAVLLPILGTSWVFGVLAVNGCAVVFQYMFATLNSLQGLFIFLFHCLLNSEVRAAFK 682
Cdd:cd15992  192 RTAFTVLLLVSVTCLLALLSVNSDVILFHYLFAGFNCLQGPFIFLSHVVLLKEVRKALK 250

brain-specific angiogenesis inhibitor 2, a group VII adhesion GPCR, member of the class B2 family of seven-transmembrane G protein-coupled receptors; Brain-specific angiogenesis inhibitors (BAI1-3) constitute the group VII of cell-adhesion receptors that have been implicated in vascularization of glioblastomas. They belong to the B2 subfamily of class B GPCRs, are predominantly expressed in the brain, and are only present in vertebrates. Three BAIs, like all adhesion receptors, are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, that are coupled to a class B seven-transmembrane domain. For example, BAI1 N-terminus contain an integrin-binding RGD (Arg-Gly-Asp) motif in addition to five thrombospondin type 1 repeats (TSRs), which are known to regulate the anti-angiogenic activity of thrombospondin-1, whereas BAI2 and BAI3 have four TSRs, but do not possess RGD motifs. The TSRs are functionally involved in cell attachment, activation of latent TGF-beta, inhibition of angiogenesis and endothelial cell migration. The TSRs of BAI1 mediates direct binding to phosphatidylserine, which enables both recognition and internalization of apoptotic cells by phagocytes. Thus, BAI1 functions as a phosphatidylserine receptor that forms a trimeric complex with ELMO and Dock180, leading to activation of Rac-GTPase which promotes the binding and phagocytosis of apoptotic cells. BAI3 can also interact with the ELMO-Dock180 complex to activate the Rac pathway and can also bind to secreted C1ql proteins of the C1Q complement family via its N-terminal TSRs. BAI3 and its ligands C1QL1 are highly expressed during synaptogenesis and are involved in synapse specificity. Moreover, BAI2 acts as a transcription repressor to regulate vascular endothelial growth factor (VEGF) expression through interaction with GA-binding protein gamma (GABP). The N-terminal extracellular domains of all three BAIs also contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain, which undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif to generate N- and C-terminal fragments (NTF and CTF), a putative hormone-binding domain (HBD), and multiple N-glycosylation sites. The C-terminus of each BAI subtype ends with a conserved Gln-Thr-Glu-Val (QTEV) motif known to interact with PDZ domain-containing proteins, but only BAI1 possesses a proline-rich region, which may be involved in protein-protein interactions.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....*.
gi 767973897 628 VLLPILGTSWVFGVLAV-NGCAVVFQYMFATLNSLQGLFIFLFHCLLNSEVRAAFK 682
Cdd:cd15988  231 VVLPLLALTWMSAVLAMtDRRSILFQVLFAVFNSVQGFVIITVHCFLRREVQDVVK 286

corticotropin-releasing factor receptor 1, member of the class B family of seven-transmembrane G protein-coupled receptors; The vertebrate corticotropin-releasing factor (CRF) receptors are predominantly expressed in central nervous system with high levels in cortex tissue, brain stem, and pituitary. They have two isoforms as a result of alternative splicing of the same receptor gene: CRF-R1 and CRF-R2, which differ in tissue distribution and ligand binding affinities. Recently, a third CRF receptor (CRF-R3) has been identified in catfish pituitary. The catfish CRF-R1 is highly homologous to CRF-R3. CRF is a 41-amino acid neuropeptide that plays a central role in coordinating neuroendocrine, behavioral, and autonomic responses to stress by acting as the primary neuroregulator of the hypothalamic-pituitary-adrenal axis, which controls the levels of cortisol and other stress related hormones. In addition, the CRF family of neuropeptides also includes structurally related peptides such as mammalian urocortin, fish urotensin I, and frog sauvagine. The actions of CRF and CRF-related peptides are mediated through specific binding to CRF-R1 and CRF-R2. CRF and urocortin 1 bind and activate mammalian CRF-R1 with similar high affinities. By contrast, urocortin 2 and urocortin 3 do not bind to CRF-R1 or stimulate CRF-R1-mediated cAMP formation. Urocortin 1 also shows high affinity for mammalian CRF-R2, whereas CRF has significantly lower affinity for this receptor. These evidence suggest that urocortin 1 is an endogenous ligand for CRF-R1 and CRF-R2. The CRF receptors are members of the B1 subfamily of class B GPCRs, also referred to as secretin-like receptor family, which includes receptors for polypeptide hormones of 27-141 amino-acid residues such as secretin, glucagon, glucagon-like peptide (GLP), calcitonin gene-related peptide, and parathyroid hormone (PTH). These receptors contain the large N-terminal extracellular domain (ECD), which plays a critical role in hormone recognition by binding to the C-terminal portion of the peptide. On the other hand, the N-terminal segment of the hormone induces receptor activation by interacting with the receptor transmembrane domains and connecting extracellular loops, triggering intracellular signaling pathways. All members of the B1 subfamily preferentially couple to G proteins of G(s) family, which positively stimulate adenylate cyclase, leading to increased intracellular cAMP formation and calcium influx. However, depending on its cellular location and function, CRF receptors can activate multiple G proteins, which can in turn stimulate different second messenger pathways.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 767973897 619 FKLTAKAVAVLLPILGTSWVFGVLAVNG---CAVVFQYMFATLNSLQGLFIFLFHCLLNSEVRAAFKHK 684
Cdd:cd15445  194 YRKAVKATLVLLPLLGITYMLFFVNPGEdeiSRIVFIYFNSFLESFQGFFVSVFYCFLNSEVRSAVRKR 262

brain-specific angiogenesis inhibitor 1, a group VII adhesion GPCR, member of the class B2 family of seven-transmembrane G protein-coupled receptors; Brain-specific angiogenesis inhibitors (BAI1-3) constitute the group VII of cell-adhesion receptors that have been implicated in vascularization of glioblastomas. They belong to the B2 subfamily of class B GPCRs, are predominantly expressed in the brain, and are only present in vertebrates. Three BAIs, like all adhesion receptors, are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, that are coupled to a class B seven-transmembrane domain. For example, BAI1 N-terminus contain an integrin-binding RGD (Arg-Gly-Asp) motif in addition to five thrombospondin type 1 repeats (TSRs), which are known to regulate the anti-angiogenic activity of thrombospondin-1, whereas BAI2 and BAI3 have four TSRs, but do not possess RGD motifs. The TSRs are functionally involved in cell attachment, activation of latent TGF-beta, inhibition of angiogenesis and endothelial cell migration. The TSRs of BAI1 mediates direct binding to phosphatidylserine, which enables both recognition and internalization of apoptotic cells by phagocytes. Thus, BAI1 functions as a phosphatidylserine receptor that forms a trimeric complex with ELMO and Dock180, leading to activation of Rac-GTPase which promotes the binding and phagocytosis of apoptotic cells. BAI3 can also interact with the ELMO-Dock180 complex to activate the Rac pathway and can also bind to secreted C1ql proteins of the C1Q complement family via its N-terminal TSRs. BAI3 and its ligands C1QL1 are highly expressed during synaptogenesis and are involved in synapse specificity. Moreover, BAI2 acts as a transcription repressor to regulate vascular endothelial growth factor (VEGF) expression through interaction with GA-binding protein gamma (GABP). The N-terminal extracellular domains of all three BAIs also contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain, which undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif to generate N- and C-terminal fragments (NTF and CTF), a putative hormone-binding domain (HBD), and multiple N-glycosylation sites. The C-terminus of each BAI subtype ends with a conserved Gln-Thr-Glu-Val (QTEV) motif known to interact with PDZ domain-containing proteins, but only BAI1 possesses a proline-rich region, which may be involved in protein-protein interactions.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897 515 ITVHLKHRLTRKQHSeATNSSNRVFVYCAFLDFSSGEGVWSNHGCALT-RGNLTYSVCrcthltnfAILMQVVPLEVNIG 593
Cdd:cd15990  100 VTGRLRNRIIRKRFL-CLGWGLPALVVAISVGFTKAKGYGTVNYCWLSlEGGLLYAFV--------GPAAAVVLVNMVIG 170

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897 594 ILIaVTRVISQISADNYKIHGDPSAfklTAKAVAVLLPILGTSWVFGVLAV-NGCAVVFQYMFATLNSLQGLFIFLFHCL 672
Cdd:cd15990  171 ILV-FNKLVSKDGITDKKLKERAGA---SLWSSCVVLPLLALTWMSAVLAItDRRSALFQILFAVFDSLEGFVIVMVHCI 246

                        170
                 ....*....|
gi 767973897 673 LNSEVRAAFK 682
Cdd:cd15990  247 LRREVQDAVK 256

insect neuropeptide receptor subgroup B7 and related proteins, member of the class B family of seven-transmembrane G protein-coupled receptors; This subgroup includes a neuropeptide receptor found in Nilaparvata lugens (brown planthopper) and its closely related proteins from invertebrates. They belong to the B1 subfamily of class B GPCRs, also referred to as secretin-like receptor family, which includes receptors for polypeptide hormones of 27-141 amino-acid residues such as secretin, glucagon, glucagon-like peptide (GLP), calcitonin gene-related peptide, parathyroid hormone (PTH), and corticotropin-releasing factor. These receptors contain the large N-terminal extracellular domain (ECD), which plays a critical role in hormone recognition by binding to the C-terminal portion of the peptide. On the other hand, the N-terminal segment of the hormone induces receptor activation by interacting with the receptor transmembrane domains and connecting extracellular loops, triggering intracellular signaling pathways. All members of the B1 subfamily preferentially couple to G proteins of G(s) family, which positively stimulate adenylate cyclase, leading to increased intracellular cAMP formation and calcium influx. The class B GPCRs have been identified in all the vertebrates, from fishes to mammals, as well as invertebrates including Caenorhabditis elegans and Drosophila melanogaster, but are not present in plants, fungi, or prokaryotes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897 560 ALTRGNLTYSVCRCTHLTNFAILMQVVPLE----VNIGILIAVTRVI-----SQISADNYKihgdpsaFKLTAKAVAVLL 630
Cdd:cd15273  150 IVARILFENSLCWTTNSNLLNFLIIRIPIMisvlINFILFLNIVRVLlvklrSSVNEDSRR-------YKKWAKSTLVLV 222

                         90       100       110       120       130       140
                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897 631 PILGTSW----VFGVLAVNGCAVVFQYMF--ATLNSLQGLFIFLFHCLLNSEVRAAFKHK 684
Cdd:cd15273  223 PLFGVHYtiflILSYLDDTNEAVELIWLFcdQLFASFQGFFVALLYCFLNGEVRAEIQRK 282

corticotropin-releasing factor receptor 2, member of the class B family of seven-transmembrane G protein-coupled receptors; The vertebrate corticotropin-releasing factor (CRF) receptors are predominantly expressed in central nervous system with high levels in cortex tissue, brain stem, and pituitary. They have two isoforms as a result of alternative splicing of the same receptor gene: CRF-R1 and CRF-R2, which differ in tissue distribution and ligand binding affinities. Recently, a third CRF receptor (CRF-R3) has been identified in catfish pituitary. The catfish CRF-R1 is highly homologous to CRF-R3. CRF is a 41-amino acid neuropeptide that plays a central role in coordinating neuroendocrine, behavioral, and autonomic responses to stress by acting as the primary neuroregulator of the hypothalamic-pituitary-adrenal axis, which controls the levels of cortisol and other stress related hormones. In addition, the CRF family of neuropeptides also includes structurally related peptides such as mammalian urocortin, fish urotensin I, and frog sauvagine. The actions of CRF and CRF-related peptides are mediated through specific binding to CRF-R1 and CRF-R2. CRF and urocortin 1 bind and activate mammalian CRF-R1 with similar high affinities. By contrast, urocortin 2 and urocortin 3 do not bind to CRF-R1 or stimulate CRF-R1-mediated cAMP formation. Urocortin 1 also shows high affinity for mammalian CRF-R2, whereas CRF has significantly lower affinity for this receptor. These evidence suggest that urocortin 1 is an endogenous ligand for CRF-R1 and CRF-R2. The CRF receptors are members of the B1 subfamily of class B GPCRs, also referred to as secretin-like receptor family, which includes receptors for polypeptide hormones of 27-141 amino-acid residues such as secretin, glucagon, glucagon-like peptide (GLP), calcitonin gene-related peptide, and parathyroid hormone (PTH). These receptors contain the large N-terminal extracellular domain (ECD), which plays a critical role in hormone recognition by binding to the C-terminal portion of the peptide. On the other hand, the N-terminal segment of the hormone induces receptor activation by interacting with the receptor transmembrane domains and connecting extracellular loops, triggering intracellular signaling pathways. All members of the B1 subfamily preferentially couple to G proteins of G(s) family, which positively stimulate adenylate cyclase, leading to increased intracellular cAMP formation and calcium influx. However, depending on its cellular location and function, CRF receptors can activate multiple G proteins, which can in turn stimulate different second messenger pathways.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 767973897 619 FKLTAKAVAVLLPILGTSWVfgVLAVNG-----CAVVFQYMFATLNSLQGLFIFLFHCLLNSEVRAAFKHK 684
Cdd:cd15446  193 YRKAVKATLVLLPLLGITYM--LFFVNPgeddiSQIVFIYFNSFLQSFQGFFVSVFYCFLNGEVRSAARKR 261

insect neuropeptide receptor subgroup B3 and related proteins belong to subfamily B1 of hormone receptors; member of the class B secretin-like seven-transmembrane G protein-coupled receptors; This subgroup includes a neuropeptide receptor found in Bombyx mori (silk worm) and its closely related proteins from arthropods. They belong to the B1 subfamily of class B GPCRs, also referred to as secretin-like receptor family, which includes receptors for polypeptide hormones of 27-141 amino-acid residues such as secretin, glucagon, glucagon-like peptide (GLP), calcitonin gene-related peptide, parathyroid hormone (PTH), and corticotropin-releasing factor. These receptors contain the large N-terminal extracellular domain (ECD), which plays a critical role in hormone recognition by binding to the C-terminal portion of the peptide. On the other hand, the N-terminal segment of the hormone induces receptor activation by interacting with the receptor transmembrane domains and connecting extracellular loops, triggering intracellular signaling pathways. All members of the B1 subfamily preferentially couple to G proteins of G(s) family, which positively stimulate adenylate cyclase, leading to increased intracellular cAMP formation and calcium influx. The class B GPCRs have been identified in all the vertebrates, from fishes to mammals, as well as invertebrates including Caenorhabditis elegans and Drosophila melanogaster, but are not present in plants, fungi, or prokaryotes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897 585 VVPLEVNIGILIAVTRV-ISQISADNykihgDPSAFKLTAKAVAVLLPILGTSWVFGVL--AVNGCAV--VFQYMFATLN 659
Cdd:cd15262  168 LFILLVNTVLLVDIIRVlVTKLRNTE-----ENSQTKSTTRATLFLVPLFGLHFVITAYrpSTDDCDWedIYYYANYLIE 242

                         90       100
                 ....*....|....*....|...
gi 767973897 660 SLQGLFIFLFHCLLNSEVRAAFK 682
Cdd:cd15262  243 GLQGFLVAILFCYINKEVHYLIK 265

orphan adhesion receptor GPR114, member of the class B2 family of seven-transmembrane G protein-coupled receptors; GPR114 is an orphan receptor that has been classified as that belongs to the Group VIII of adhesion GPCRs. Other members of the Group VII include GPR56, GPR64, GPR97, GPR112, and GPR126. GPR114 is mainly found in granulocytes (polymorphonuclear leukocytes), and GPR114-transfected cells induced an increase in cAMP levels via coupling to G(s) protein. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, that are coupled to a class B seven-transmembrane domain. Furthermore, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR- autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897 591 NIGILIAVTRVISQISADNYKIHGDPSAFKLTAKAVAVLLpilGTSWVFGVLAVnGCAVVFQ-YMFATLNSLQGLFIFLF 669
Cdd:cd15443  177 NLVVLAWVVRMLRRLRSRKQELGERARRDWVTVLGLTCLL---GTTWALAFFSF-GVFLIPQlFLFTIINSLYGFFICLW 252

                         90
                 ....*....|....*.
gi 767973897 670 HCLLNSEVRAAFKHKT 685
Cdd:cd15443  253 YCTQRRRSDASAKSST 268

insect neuropeptide receptor subgroup B4 and related proteins, member of the class B family of seven-transmembrane G protein-coupled receptors; This subgroup includes a neuropeptide receptor found in Nilaparvata lugens (brown planthopper) and its closely related proteins from mollusks and annelid worms. They belong to the B1 subfamily of class B GPCRs, also referred to as secretin-like receptor family, which includes receptors for polypeptide hormones of 27-141 amino-acid residues such as secretin, glucagon, glucagon-like peptide (GLP), calcitonin gene-related peptide, parathyroid hormone (PTH), and corticotropin-releasing factor. These receptors contain the large N-terminal extracellular domain (ECD), which plays a critical role in hormone recognition by binding to the C-terminal portion of the peptide. On the other hand, the N-terminal segment of the hormone induces receptor activation by interacting with the receptor transmembrane domains and connecting extracellular loops, triggering intracellular signaling pathways. All members of the B1 subfamily preferentially couple to G proteins of G(s) family, which positively stimulate adenylate cyclase, leading to increased intracellular cAMP formation and calcium influx. The class B GPCRs have been identified in all the vertebrates, from fishes to mammals, as well as invertebrates including Caenorhabditis elegans and Drosophila melanogaster, but are not present in plants, fungi, or prokaryotes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897 560 ALTRGNLTYSVCRC----THLTNFAILMQVVPLEVNIGILIAVTRVI----SQISAdnykiHGDPSAFKLTAKAVAVLLP 631
Cdd:cd15260  134 AGVRASLPDDTERCwmeeSSYQWILIVPVVLSLLINLIFLINIVRVLltklRATSP-----NPAPAGLRKAVRATLILIP 208

                         90       100       110       120       130
                 ....*....|....*....|....*....|....*....|....*....|....*.
gi 767973897 632 ILGTSWVFGVLAVNGCAV---VFQYMFATLNSLQGLFIFLFHCLLNSEVRAAFKHK 684
Cdd:cd15260  209 LLGLQFLLIPFRPEPGAPletIYQYVSALLTSLQGLCVAVLFCFCNGEVIAAIKRK 264

secretin receptor-like group of hormone receptors, member of the class B family of seven-transmembrane G protein-coupled receptors; This group represents G protein-coupled receptors for structurally similar peptide hormones that include secretin, growth-hormone-releasing hormone (GHRH), pituitary adenylate cyclase activating polypeptide (PACAP), and vasoactive intestinal peptide (VIP). These receptors are classified into the subfamily B1 of class B GRCRs that consists of the classical hormone receptors and have been identified in all the vertebrates, from fishes to mammals, but are not present in plants, fungi, or prokaryotes. For all class B receptors, the large N-terminal extracellular domain plays a critical role in peptide hormone recognition. Secretin, a polypeptide secreted by entero-endocrine S cells in the small intestine, is involved in maintaining body fluid balance. This polypeptide regulates the secretion of bile and bicarbonate into the duodenum from the pancreatic and biliary ducts, as well as regulates the duodenal pH by the control of gastric acid secretion. Studies with secretin receptor-null mice indicate that secretin plays a role in regulating renal water reabsorption. Secretin mediates its biological actions by elevating intracellular cAMP via G protein-coupled secretin receptors, which are expressed in the brain, pancreas, stomach, kidney, and liver. GHRHR is a specific receptor for the growth hormone-releasing hormone (GHRH) that controls the synthesis and release of growth hormone (GH) from the anterior pituitary somatotrophs. Mutations in the gene encoding GHRHR have been connected to isolated growth hormone deficiency (IGHD), a short-stature condition caused by deficient production of GH or lack of GH action. VIP and PACAP exert their effects through three G protein-coupled receptors, PACAP-R1, VIP-R1 (vasoactive intestinal receptor type 1, also known as VPAC1) and VIP-R2 (or VPAC2). PACAP-R1 binds only PACAP with high affinity, whereas VIP-R1 and -R2 specifically bind and respond to both VIP and PACAP. VIP and PACAP and their receptors are widely expressed in the brain and periphery. They are upregulated in neurons and immune cells in responses to CNS injury and/or inflammation and exert potent anti-inflammatory effects, as well as play important roles in the control of circadian rhythms and stress responses, among many others. All B1 subfamily GPCRs are able to increase intracellular cAMP levels by coupling to adenylate cyclase via a stimulatory Gs protein. However, depending on its cellular location, some members of subfamily B1 are also capable of coupling to additional G proteins such as G(i/o) and/or G(q) proteins, thereby leading to activation of phospholipase C and intracellular calcium influx.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767973897 590 VNIGILIAVTRVISQISADNYKIHGDPSAFKLTAKAVAVLLPILGTSW-VFGVLAVNGCAVVFQYMFATLNSLQGLFIFL 668
Cdd:cd15930  170 VNFVLFINIIRILLQKLRSPDIGGNESSQYKRLARSTLLLIPLFGIHYiVFAFFPENISLGIRLYFELCLGSFQGFVVAV 249

                         90
                 ....*....|....*.
gi 767973897 669 FHCLLNSEVRAAFKHK 684
Cdd:cd15930  250 LYCFLNGEVQAEIKRK 265