Immunoglobulin domain; The members here are composed of the immunoglobulin (Ig) domain found in the Ig superfamily. The Ig superfamily is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. Members of this group are components of immunoglobulin, neuroglia, cell surface glycoproteins, including T-cell receptors, CD2, CD4, CD8, and membrane glycoproteins, including butyrophilin and chondroitin sulfate proteoglycan core protein. A predominant feature of most Ig domains is a disulfide bridge connecting the two beta-sheets with a tryptophan residue packed against the disulfide bond. Ig superfamily (IgSF) domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. Typically, the V-set domains have A, B, E, and D strands in one sheet and A', G, F, C, C' and C" in the other. The structures in C1-set are smaller than those in the V-set; they have one beta sheet that is formed by strands A, B, E, and D and the other by strands G, F, C, and C'. Moreover, a C1-set Ig domain contains a short C' strand (three residues) and lacks A' and C" strand. Unlike other Ig domain sets, C2-set structures do not have a D strand. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391 288 PMITHRTPKVAVSEGQSVSLKCKAVGDPDPYVRWIAPDGKLVSNTSRTTSYENGTLDLVGTSLGDKGTFTCIASNAAGES 367
Cdd:cd05764    1 PLITRHTHELRVLEGQRATLRCKARGDPEPAIHWISPEGKLISNSSRTLVYDNGTLDILITTVKDTGAFTCIASNPAGEA 80

                 ....*...
gi 326936391 368 TAPVELVV 375
Cdd:cd05764   81 TARVELHI 88

Leucine rich repeat C-terminal domain;

                           10        20        30
                   ....*....|....*....|....*....|....*.
gi 326936391   241 NPLHCNCELVWLRRLTREDDLE------TCASPPEL 270
Cdd:smart00082   1 NPFICDCELRWLLRWLQANEHLqdpvdlRCASPSSL 36

Immunoglobulin domain of human Synaptic Adhesion-Like Molecule 5 (SALM5) and similar proteins; member of the I-set of IgSF domains; This group contains the immunoglobulin domain of human Synaptic Adhesion-Like Molecule 5 (SALM5) and similar proteins. The SALM (for synaptic adhesion-like molecules; also known as Lrfn for leucine-rich repeat and fibronectin type III domain containing) family of adhesion molecules consists of five known members: SALM1/Lrfn2, SALM2/Lrfn1, SALM3/Lrfn4, SALM4/Lrfn3, and SALM5/Lrfn5. SALMs share a similar domain structure, containing leucine-rich repeats (LRRs), an immunoglobulin (Ig) domain, and a fibronectin III (FNIII) domain, followed by a transmembrane domain and a C-terminal PDZ-binding motif. SALM5 is implicated in autism spectrum disorders (ASDs) and schizophrenia, induces presynaptic differentiation in contacting axons. SALM5 interacts with the Ig domains of LAR (Leukocyte common Antigen-Related) family receptor protein tyrosine phosphatases (LAR-RPTPs; LAR, PTPdelta, and PTPsigma). In addition, PTPdelta is implicated in ASDs, ADHD, bipolar disorder, and restless leg syndrome. Studies have shown that LAR-RPTPs are novel and splicing-dependent presynaptic ligands for SALM5, and that they mediate SALM5-dependent presynaptic differentiation. Furthermore, SALM5 maintains AMPA receptor (AMPAR)-mediated excitatory synaptic transmission through mechanisms involving the interaction of SALM5 with LAR-RPTPs. This group belongs to the I-set of immunoglobulin superfamily (IgSF) domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand but lack a C" strand.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391 288 PMITHRTPKVAVSEGQSVSLKCKAVGDPDPYVRWIAPDGKLVSNTSRTTSYENGTLDLVGTSLGDKGTFTCIASNAAGES 367
Cdd:cd05764    1 PLITRHTHELRVLEGQRATLRCKARGDPEPAIHWISPEGKLISNSSRTLVYDNGTLDILITTVKDTGAFTCIASNPAGEA 80

                 ....*...
gi 326936391 368 TAPVELVV 375
Cdd:cd05764   81 TARVELHI 88

Immunoglobulin I-set domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391  288 PMITHRTPKVAVSEGQSVSLKCKAVGDPDPYVRWIAPDGKLVSNTSRTTSYENG--TLDLVGTSLGDKGTFTCIASNAAG 365
Cdd:pfam07679   1 PKFTQKPKDVEVQEGESARFTCTVTGTPDPEVSWFKDGQPLRSSDRFKVTYEGGtyTLTISNVQPDDSGKYTCVATNSAG 80

                          90
                  ....*....|
gi 326936391  366 ESTAPVELVV 375
Cdd:pfam07679  81 EAEASAELTV 90

Leucine rich repeat;

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 326936391  100 GLHALHLDSNRLTYINEDHFKGLINLRHLILSNNQLSYISPGSLDDFiETIEDLDLSYNNL 160
Cdd:pfam13855   2 NLRSLDLSNNRLTSLDDGAFKGLSNLKVLDLSNNLLTTLSPGAFSGL-PSLRYLDLSGNRL 61

leucine-rich repeat receptor-like protein kinase; Provisional

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391  70 DFANMTNLIHLTLSRNTISQIMPYAFFDLKGLHALHLDSNRLTYINEDHFKGLINLRHLILSNNQLSYISPGSLDDFiET 149
Cdd:PLN00113 470 DSFGSKRLENLDLSRNQFSGAVPRKLGSLSELMQLKLSENKLSGEIPDELSSCKKLVSLDLSHNQLSGQIPASFSEM-PV 548

                         90       100       110
                 ....*....|....*....|....*....|....*...
gi 326936391 150 IEDLDLSYNNLVNvpwETVAKLSNVNT---VSLDHNLI 184
Cdd:PLN00113 549 LSQLDLSQNQLSG---EIPKNLGNVESlvqVNISHNHL 583

Immunoglobulin domain of human Synaptic Adhesion-Like Molecule 5 (SALM5) and similar proteins; member of the I-set of IgSF domains; This group contains the immunoglobulin domain of human Synaptic Adhesion-Like Molecule 5 (SALM5) and similar proteins. The SALM (for synaptic adhesion-like molecules; also known as Lrfn for leucine-rich repeat and fibronectin type III domain containing) family of adhesion molecules consists of five known members: SALM1/Lrfn2, SALM2/Lrfn1, SALM3/Lrfn4, SALM4/Lrfn3, and SALM5/Lrfn5. SALMs share a similar domain structure, containing leucine-rich repeats (LRRs), an immunoglobulin (Ig) domain, and a fibronectin III (FNIII) domain, followed by a transmembrane domain and a C-terminal PDZ-binding motif. SALM5 is implicated in autism spectrum disorders (ASDs) and schizophrenia, induces presynaptic differentiation in contacting axons. SALM5 interacts with the Ig domains of LAR (Leukocyte common Antigen-Related) family receptor protein tyrosine phosphatases (LAR-RPTPs; LAR, PTPdelta, and PTPsigma). In addition, PTPdelta is implicated in ASDs, ADHD, bipolar disorder, and restless leg syndrome. Studies have shown that LAR-RPTPs are novel and splicing-dependent presynaptic ligands for SALM5, and that they mediate SALM5-dependent presynaptic differentiation. Furthermore, SALM5 maintains AMPA receptor (AMPAR)-mediated excitatory synaptic transmission through mechanisms involving the interaction of SALM5 with LAR-RPTPs. This group belongs to the I-set of immunoglobulin superfamily (IgSF) domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand but lack a C" strand.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391 288 PMITHRTPKVAVSEGQSVSLKCKAVGDPDPYVRWIAPDGKLVSNTSRTTSYENGTLDLVGTSLGDKGTFTCIASNAAGES 367
Cdd:cd05764    1 PLITRHTHELRVLEGQRATLRCKARGDPEPAIHWISPEGKLISNSSRTLVYDNGTLDILITTVKDTGAFTCIASNPAGEA 80

                 ....*...
gi 326936391 368 TAPVELVV 375
Cdd:cd05764   81 TARVELHI 88

Leucine-rich repeat (LRR) protein [Transcription];

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391  55 ELRLMDNFITTLRrKDFANMTNLIHLTLSRNTISQImPYAFFDLKGLHALHLDSNRLTYINEDhFKGLINLRHLILSNNQ 134
Cdd:COG4886  140 ELDLSNNQLTDLP-EPLGNLTNLKSLDLSNNQLTDL-PEELGNLTNLKELDLSNNQITDLPEP-LGNLTNLEELDLSGNQ 216

                         90       100       110       120       130       140       150
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 326936391 135 LSYIsPGSLDDFiETIEDLDLSYNNLVNVPWetVAKLSNVNTVSLDHNLIEFVPEgiFSNLHKLARLDMTSNKLKKI 211
Cdd:COG4886  217 LTDL-PEPLANL-TNLETLDLSNNQLTDLPE--LGNLTNLEELDLSNNQLTDLPP--LANLTNLKTLDLSNNQLTDL 287

Immunoglobulin like; IG domains that cannot be classified into one of IGv1, IGc1, IGc2, IG.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391   295 PKVAVSEGQSVSLKCKAVGDPDPYVRWIAPDGKLVSNTSRTTSYENG---TLDLVGTSLGDKGTFTCIASNAAGESTAPV 371
Cdd:smart00410   2 PSVTVKEGESVTLSCEASGSPPPEVTWYKQGGKLLAESGRFSVSRSGstsTLTISNVTPEDSGTYTCAATNSSGSASSGT 81

                   ....
gi 326936391   372 ELVV 375
Cdd:smart00410  82 TLTV 85

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 326936391  287 PPMITHRTPKVAVSEGQSVSLKCKAVGDPDPYVRWIAPDGKLVSNTSR--TTSYENGTLDLVGTSLGDKGTFTCIASN 362
Cdd:pfam13927   1 KPVITVSPSSVTVREGETVTLTCEATGSPPPTITWYKNGEPISSGSTRsrSLSGSNSTLTISNVTRSDAGTYTCVASN 78

Immunoglobulin I-set domain of the Leucine-rich repeat and immunoglobin-like domain-containing protein 1 (Lingo-1); The members here are composed of the immunoglobulin I-set (IgI) domain of the Leucine-rich repeat and immunoglobin-like domain-containing protein 1 (Lingo-1). Human Lingo-1 is a central nervous system-specific transmembrane glycoprotein also known as LERN-1, which functions as a negative regulator of neuronal survival, axonal regeneration, and oligodendrocyte differentiation and myelination. Lingo-1 is a key component of the Nogo receptor signaling complex (RTN4R/NGFR) in RhoA activation responsible for some inhibition of axonal regeneration by myelin-associated factors. The ligand-binding ectodomain of human Lingo-1 contains a bimodular, kinked structure composed of leucine-rich repeat (LRR) and immunoglobulin (Ig)-like modules. Diseases associated with Lingo-1 include mental retardation, autosomal recessive 64 and essential tremor. The Ig superfamily (IgSF) is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. IgSF domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. Unlike the V-set, one of the distinctive features of I-set domains is the lack of a C" strand. The structure of the Lingo-1 lacks this strand and thus it belongs to the I-set of the IgSF. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors, the hemolymph protein hemolin, the muscle proteins titin, telokin, and twitchin, the neuronal adhesion molecule axonin-1, and the signaling molecule semaphorin 4D that is involved in axonal guidance, immune function and angiogenesis.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391 297 VAVSEGQSVSLKCKAVGDPDPYVRWIAPDGKLVSNTS--RTTSYENGTLDLVGTSLGDKGTFTCIASNAAGESTAPVELV 374
Cdd:cd20969   12 VFVDEGHTVQFVCRADGDPPPAILWLSPRKHLVSAKSngRLTVFPDGTLEVRYAQVQDNGTYLCIAANAGGNDSMPAHLH 91

                 .
gi 326936391 375 V 375
Cdd:cd20969   92 V 92

Fifth Ig-like domain of Roundabout (Robo) homolog 1/2, and similar domains; a member of the I-set of IgSF domains; The members here are composed of the fifth Ig-like domain of Roundabout (Robo) homolog 1/2 and similar domains. Robo receptors play a role in the development of the central nervous system (CNS), and are receptors of Slit protein. Slit is a repellant secreted by the neural cells in the midline. Slit acts through Robo to prevent most neurons from crossing the midline from either side. Three mammalian Robo homologs (Robo1, -2, and -3), and three mammalian Slit homologs (Slit-1,-2, -3), have been identified. Commissural axons, which cross the midline, express low levels of Robo; longitudinal axons, which avoid the midline, express high levels of Robo. Robo1, -2, and -3 are expressed by commissural neurons in the vertebrate spinal cord and Slits 1, -2, -3 are expressed at the ventral midline. Robo-3 is a divergent member of the Robo family which instead of being a positive regulator of slit responsiveness, antagonizes slit responsiveness in precrossing axons. The Slit-Robo interaction is mediated by the second leucine-rich repeat (LRR) domain of Slit and the two N-terminal Ig domains of Robo, Ig1 and Ig2. The primary Robo binding site for Slit2 has been shown by surface plasmon resonance experiments and mutational analysis to be is the Ig1 domain, while the Ig2 domain has been proposed to harbor a weak secondary binding site. The fifth Ig-like domain of Robo 1 and 2 is a member of the I-set Ig domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand but lack a C" strand. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391 297 VAVSEGQSVSLKCKAVGDPDPYVRWIApDGKLVS-NTSRTTSYENGTLDLVGTSLGDKGTFTCIASNAAGESTAPVELVV 375
Cdd:cd20952    9 QTVAVGGTVVLNCQATGEPVPTISWLK-DGVPLLgKDERITTLENGSLQIKGAEKSDTGEYTCVALNLSGEATWSAVLDV 87

Fourth immunoglobulin (Ig)-like domain of hemolin, and similar domains; a member of the I-set of IgSF domains; The members here are composed of the fourth immunoglobulin (Ig)-like domain of hemolin and similar proteins. Hemolin, an insect immunoglobulin superfamily (IgSF) member containing four Ig-like domains, is a lipopolysaccharide-binding immune protein induced during bacterial infection. Hemolin shares significant sequence similarity with the first four Ig-like domains of the transmembrane cell adhesion molecules (CAMs) of the L1 family. IgSF domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. The fourth Ig-like domain of hemolin is a member of the I-set Ig domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set domains, members of the I-set have a discontinuous A strand but lack a C" strand. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors, the muscle proteins titin, telokin, and twitchin, the neuronal adhesion molecule axonin-1, and the signaling molecule semaphorin 4D that is involved in axonal guidance, immune function and angiogenesis.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 326936391 297 VAVSEGQSVSLKCKAVGDPDPYVRWIApDGKLVSNTSRTTSYENGTLDLVGTSLGDKGTFTCIASNAAGESTAPVELVV 375
Cdd:cd20978   11 VVVKGGQDVTLPCQVTGVPQPKITWLH-NGKPLQGPMERATVEDGTLTIINVQPEDTGYYGCVATNEIGDIYTETLLHV 88

Leucine rich repeat;

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 326936391   75 TNLIHLTLSRNTISQIMPYAFFDLKGLHALHLDSNRLTYINEDHFKGLINLRHLILSNNQL 135
Cdd:pfam13855   1 PNLRSLDLSNNRLTSLDDGAFKGLSNLKVLDLSNNLLTTLSPGAFSGLPSLRYLDLSGNRL 61

Second immunoglobulin (Ig)-like domain of fibroblast growth factor (FGF) receptor_like-1(FGFRL1); member of the I-set of IgSF domains; The members here are composed of the second immunoglobulin (Ig)-like domain of fibroblast growth factor (FGF) receptor like-1(FGFRL1). FGFRL1 is comprised of a signal peptide, three extracellular Ig-like modules, a transmembrane segment, and a short intracellular domain. FGFRL1 is expressed preferentially in skeletal tissues. Similar to FGF receptors, the expressed protein interacts specifically with heparin and with FGF2. FGFRL1 does not have a protein tyrosine kinase domain at its C-terminus; neither does its cytoplasmic domain appear to interact with a signaling partner. It has been suggested that FGFRL1 may not have any direct signaling function, but instead acts as a decoy receptor trapping FGFs and preventing them from binding other receptors.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391 293 RTPKVAVSEGQSVSLKCKAVGDPDPYVRWIAPDGKLVSNTSRTTSYENGTLDLVGTSLGDKGTFTCIASNAAGESTAPVE 372
Cdd:cd05856   10 RRRVIARPVGSSVRLKCVASGNPRPDITWLKDNKPLTPPEIGENKKKKWTLSLKNLKPEDSGKYTCHVSNRAGEINATYK 89

                 ...
gi 326936391 373 LVV 375
Cdd:cd05856   90 VDV 92

Second Ig-like domain of the giant muscle protein titin Z1z2 in the sarcomeric Z-disk, and similar domains; a member of the I-set of IgSF domains; The members here are composed of the second immunoglobulin (Ig)-like domain of the giant muscle protein titin Z1z2 in the sarcomeric Z-disk and similar proteins. Titin is a key component in the assembly and functioning of vertebrate striated muscles. By providing connections at the level of individual microfilaments, it contributes to the fine balance of forces between the two halves of the sarcomere. The Ig superfamily (IgSF) is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. IgSF domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. Unlike the V-set, one of the distinctive features of I-set domains is the lack of a C" strand. The structure of the titin Z1z2 lacks this strand and thus it belongs to the I-set of the IgSF. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors, the hemolymph protein hemolin, the muscle proteins titin, telokin, and twitchin, the neuronal adhesion molecule axonin-1, and the signaling molecule semaphorin 4D that is involved in axonal guidance, immune function and angiogenesis.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391 287 PPMITHRTPKVAVSEGQSVSLKCKAVGDPDPYVRWIApDGKLVSNTSRTTSYENG---TLDLVGTSLGDKGTFTCIASNA 363
Cdd:cd20972    1 PPQFIQKLRSQEVAEGSKVRLECRVTGNPTPVVRWFC-EGKELQNSPDIQIHQEGdlhSLIIAEAFEEDTGRYSCLATNS 79

                         90
                 ....*....|..
gi 326936391 364 AGESTAPVELVV 375
Cdd:cd20972   80 VGSDTTSAEIFV 91

Immunoglobulin (Ig)-like domain of myotilin, palladin, and myopalladin; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the immunoglobulin (Ig)-like domain in myotilin, palladin, and myopalladin. Myotilin, palladin, and myopalladin function as scaffolds that regulate actin organization. Myotilin and myopalladin are most abundant in skeletal and cardiac muscle; palladin is ubiquitously expressed in the organs of developing vertebrates and plays a key role in cellular morphogenesis. The three family members each interact with specific molecular partners with all three binding to alpha-actinin; In addition, palladin also binds to vasodilator-stimulated phosphoprotein (VASP) and ezrin, myotilin binds to filamin and actin, and myopalladin also binds to nebulin and cardiac ankyrin repeat protein (CARP). This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391 288 PMITHRTPKVAVSEGQSVSLKCKAVGDPDPYVRWIApDGKLVSNTSRTTSY--ENGTLDLVGTSLG--DKGTFTCIASNA 363
Cdd:cd05744    1 PHFLQAPGDLEVQEGRLCRFDCKVSGLPTPDLFWQL-NGKPVRPDSAHKMLvrENGRHSLIIEPVTkrDAGIYTCIARNR 79

                         90
                 ....*....|..
gi 326936391 364 AGESTAPVELVV 375
Cdd:cd05744   80 AGENSFNAELVV 91

Fourth immunoglobulin domain of the Drosophila melanogaster Dscam protein, and similar domains; a member of the I-set of IgSF domains; The members here are composed of the fourth immunoglobulin domain of the Drosophila melanogaster Down syndrome cell adhesion molecule (DSCAM) protein and similar proteins. Down syndrome cell adhesion molecule (DSCAM) is a cell adhesion molecule that plays critical roles in neural development, including axon guidance and branching, axon target recognition, self-avoidance and synaptic formation. DSCAM belongs to the immunoglobulin superfamily and contributes to defects in the central nervous system in Down syndrome patients. Vertebrate DSCAMs differ from Drosophila Dscam1 in that they lack the extensive alternative splicing that occurs in the insect gene. Drosophila melanogaster Dscam has 38,016 isoforms generated by the alternative splicing of four variable exon clusters, which allows every neuron in the fly to display a distinctive set of Dscam proteins on its cell surface. Drosophila Dscam1 is a cell-surface protein that plays important roles in neural development and axon tiling of neurons. It is shown that thousands of isoforms bind themselves through specific homophilic (self-binding) interactions, a process which mediates cellular self-recognition. Drosophila Dscam2 is also alternatively spliced and plays a key role in the development of two visual system neurons, monopolar cells L1 and L2. This group is a member of the I-set Ig domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand but lack a C" strand.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391 287 PPMITHRTPKVAVSEGQSVSLKCKAVGDPDPYVRWIApDGKLVSNTSRTT--SYENGTLDLVG----TSL--GDKGTFTC 358
Cdd:cd20956    1 APVLLETFSEQTLQPGPSVSLKCVASGNPLPQITWTL-DGFPIPESPRFRvgDYVTSDGDVVSyvniSSVrvEDGGEYTC 79

                 ....*...
gi 326936391 359 IASNAAGE 366
Cdd:cd20956   80 TATNDVGS 87

immunoglobulin-like domain of telokin and similar proteins; a member of the I-set of IgSF domains; The members here are composed of the immunoglobulin (Ig) domain in telokin, the C-terminal domain of myosin light chain kinase which is identical to telokin, and similar proteins. The Ig superfamily (IgSF) is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. IgSF domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. Unlike the V-set, one of the distinctive features of I-set domains is the lack of a C" strand. The structure of the telokin Ig domain lacks this strand and thus it belongs to the I-set of the IgSF. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors, the hemolymph protein hemolin, the muscle proteins titin, telokin, and twitchin, the neuronal adhesion molecule axonin-1, and the signaling molecule semaphorin 4D that is involved in axonal guidance, immune function and angiogenesis.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391 299 VSEGQSVSLKCKAVGDPDPYVRWIAPDGKLVSNTSRTTSYE---NGTLDLVGTSLGDKGTFTCIASNAAGESTAPVELVV 375
Cdd:cd20973    9 VVEGSAARFDCKVEGYPDPEVKWMKDDNPIVESRRFQIDQDedgLCSLIISDVCGDDSGKYTCKAVNSLGEATCSAELTV 88

Third immunoglobulin (Ig)-like domain of Neural Cell Adhesion Molecule 1 (NCAM-1); member of the I-set of IgSF domains; The members here are composed of the third immunoglobulin (Ig)-like domain of Neural Cell Adhesion Molecule (NCAM-1). NCAM plays important roles in the development and regeneration of the central nervous system, in synaptogenesis and neural migration. NCAM mediates cell-cell and cell-substratum recognition and adhesion via homophilic (NCAM-NCAM), and heterophilic (NCAM-non-NCAM), interactions. NCAM is expressed as three major isoforms having different intracellular extensions. The extracellular portion of NCAM has five N-terminal Ig-like domains and two fibronectin type III domains. The double zipper adhesion complex model for NCAM homophilic binding involves Ig1, Ig2, and Ig3. By this model, Ig1 and Ig2 mediate dimerization of NCAM molecules situated on the same cell surface (cis interactions), and Ig3 domains mediate interactions between NCAM molecules expressed on the surface of opposing cells (trans interactions) through binding to the Ig1 and Ig2 domains. The adhesive ability of NCAM is modulated by the addition of polysialic acid chains to the fifth Ig-like domain.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391 287 PPMITHRTPKVAVSE--GQSVSLKCKAVGDPDPYVRWIApDGKLVSNTSRTTSY-ENGT-LDLVGTSLGDKGTFTCIASN 362
Cdd:cd05730    1 PPTIRARQSEVNATAnlGQSVTLACDADGFPEPTMTWTK-DGEPIESGEEKYSFnEDGSeMTILDVDKLDEAEYTCIAEN 79

                         90
                 ....*....|...
gi 326936391 363 AAGESTAPVELVV 375
Cdd:cd05730   80 KAGEQEAEIHLKV 92

Fourth Ig domain of the neural cell adhesion molecule contactin-2, and similar domains; The members here are composed of the fourth Ig domain of the neural cell adhesion molecule contactin-2. Contactins are comprised of six Ig domains followed by four fibronectin type III (FnIII) domains anchored to the membrane by glycosylphosphatidylinositol. Contactin-2 (also called TAG-1, axonin-1) facilitates cell adhesion by homophilic binding between molecules in apposed membranes. The first four Ig domains form the intermolecular binding fragment which arranges as a compact U-shaped module by contacts between Ig domains 1 and 4, and domains 2 and 3. It has been proposed that a linear zipper-like array forms, from contactin-2 molecules alternatively provided by the two apposed membranes.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 326936391 302 GQSVSLKCKAVGDPDPYVRWIApDGKLVSNTSRTtSYENGTLDLVGTSLGDKGTFTCIASNAAGESTAPVELVV 375
Cdd:cd05728   14 GSSLRWECKASGNPRPAYRWLK-NGQPLASENRI-EVEAGDLRITKLSLSDSGMYQCVAENKHGTIYASAELAV 85

protein phosphatase 1 regulatory subunit 42; Protein phosphatase 1 regulatory subunit 42 (PPP1R42), also known as leucine-rich repeat-containing protein 67 (lrrc67) or testis leucine-rich repeat (TLRR) protein, plays a role in centrosome separation. PPP1R42 has been shown to interact with the well-conserved signaling protein phosphatase-1 (PP1) and thereby increasing PP1's activity, which counters centrosome separation. Inhibition of PPP1R42 expression increases the number of centrosomes per cell while its depletion reduces the activity of PP1 leading to activation of NEK2, the kinase responsible for phosphorylation of centrosomal linker proteins promoting centrosome separation.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391  56 LRLMDNFITTLrrKDFANMTNLIHLTLSRNTISQIMPYAFfdLKGLHALHLDSNRLTYIneDHFKGLINLRHLILSNNQL 135
Cdd:cd21340    7 LYLNDKNITKI--DNLSLCKNLKVLYLYDNKITKIENLEF--LTNLTHLYLQNNQIEKI--ENLENLVNLKKLYLGGNRI 80

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391 136 S--------------YIS-------------PGSLDDFIETIEDLDLSYNNLVNVpwETVAKLSNVNTVSLDHNLIEFVP 188
Cdd:cd21340   81 SvveglenltnleelHIEnqrlppgekltfdPRSLAALSNSLRVLNISGNNIDSL--EPLAPLRNLEQLDASNNQISDLE 158

                        170       180
                 ....*....|....*....|....*.
gi 326936391 189 E--GIFSNLHKLARLDMTSNKLKKIP 212
Cdd:cd21340  159 EllDLLSSWPSLRELDLTGNPVCKKP 184

First immunoglobulin (Ig)-like domain of neural cell adhesion molecule NCAM-1, and similar domains; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the first immunoglobulin (Ig)-like domain of neural cell adhesion molecule NCAM-1. NCAM-1 plays important roles in the development and regeneration of the central nervous system, in synaptogenesis and neural migration. NCAM mediates cell-cell and cell-substratum recognition and adhesion via homophilic (NCAM-NCAM) and heterophilic (NCAM-nonNCAM) interactions. NCAM is expressed as three major isoforms having different intracellular extensions. The extracellular portion of NCAM has five N-terminal Ig-like domains and two fibronectin type III domains. The double zipper adhesion complex model for NCAM homophilic binding involves the Ig1, Ig2, and Ig3 domains. By this model, Ig1 and Ig2 mediate dimerization of NCAM molecules situated on the same cell surface (cis interactions), and Ig3 domains mediate interactions between NCAM molecules expressed on the surface of opposing cells (trans interactions), through binding to the Ig1 and Ig2 domains. The adhesive ability of NCAM is modulated by the addition of polysialic acid chains to the fifth Ig-like domain. Also included in this group is NCAM-2 (also known as OCAM/mamFas II and RNCAM). NCAM-2 is differentially expressed in the developing and mature olfactory epithelium (OE). This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391 295 PKVAVSEGQSVSLKCKAVGDPDPyVRWIAPDG-KLVSNTSRTTSYENG----TLDLVGTSLGDKGTFTCIASNAAG-EST 368
Cdd:cd04977    8 SYAEISVGESKFFLCKVSGDAKN-INWVSPNGeKVLTKHGNLKVVNHGsvlsSLTIYNANINDAGIYKCVATNGKGtESE 86

                 ....*
gi 326936391 369 APVEL 373
Cdd:cd04977   87 ATVKL 91

Immunoglobulin (Ig)-like domain of human titin C terminus and similar proteins; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the fifth immunoglobulin (Ig)-like domain from the C-terminus of human titin x and similar proteins. Titin (also called connectin) is a fibrous sarcomeric protein specifically found in vertebrate striated muscle. Titin is gigantic; depending on isoform composition it ranges from 2970 to 3700 kDa, and is of a length that spans half a sarcomere. Titin largely consists of multiple repeats of Ig-like and fibronectin type 3 (FN-III)-like domains. Titin connects the ends of myosin thick filaments to Z disks and extends along the thick filament to the H zone and appears to function similar to an elastic band, keeping the myosin filaments centered in the sarcomere during muscle contraction or stretching. This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391 287 PPMITHRTPKVAVSEGQSVSLKCKAVGDPDPYVRWIApDGKLVSNTSR----TTSYENgTLDLVGTSLGDKGTFTCIASN 362
Cdd:cd05747    3 PATILTKPRSLTVSEGESARFSCDVDGEPAPTVTWMR-EGQIIVSSQRhqitSTEYKS-TFEISKVQMSDEGNYTVVVEN 80

                         90
                 ....*....|.
gi 326936391 363 AAGESTAPVEL 373
Cdd:cd05747   81 SEGKQEAQFTL 91

Second immunoglobulin (Ig)-like domain of fibroblast growth factor (FGF) receptor, and similar domains; member of the I-set of IgSF domains; The members here are composed of the second immunoglobulin (Ig)-like domain of fibroblast growth factor (FGF) receptor. FGF receptors bind FGF signaling polypeptides. FGFs participate in multiple processes such as morphogenesis, development, and angiogenesis. FGFs bind to four FGF receptor tyrosine kinases (FGFR1, FGFR2, FGFR3, FGFR4). Receptor diversity is controlled by alternative splicing producing splice variants with different ligand binding characteristics and different expression patterns. FGFRs have an extracellular region comprised of three Ig-like domains, a single transmembrane helix, and an intracellular tyrosine kinase domain. Ligand binding and specificity reside in the Ig-like domains 2 and 3, and the linker region that connects these two. FGFR activation and signaling depend on FGF-induced dimerization, a process involving cell surface heparin or heparin sulfate proteoglycans. This group also contains fibroblast growth factor (FGF) receptor like-1(FGFRL1). FGFRL1 does not have a protein tyrosine kinase domain at its C-terminus; neither does its cytoplasmic domain appear to interact with a signaling partner. It has been suggested that FGFRL1 may not have any direct signaling function, but instead acts as a decoy receptor trapping FGFs and preventing them from binding other receptors.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 326936391 293 RTPKVAVSEGQSVSLKCKAVGDPDPYVRWIApDGKLVSNTSRTTSYENG----TLDLVGTSLGDKGTFTCIASNAAGE 366
Cdd:cd05729   10 EEREHALPAANKVRLECGAGGNPMPNITWLK-DGKEFKKEHRIGGTKVEekgwSLIIERAIPRDKGKYTCIVENEYGS 86

Third immunoglobulin (Ig)-like domain of peroxidasin; The members here are composed of the third immunoglobulin (Ig)-like domain in peroxidasin. Peroxidasin has a peroxidase domain and interacting extracellular motifs containing four Ig-like domains. It has been suggested that peroxidasin is secreted and has functions related to the stabilization of the extracellular matrix. It may play a part in various other important processes such as removal and destruction of cells which have undergone programmed cell death and protection of the organism against non-self.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 326936391 301 EGQSVSLKCKAVGDPDPYVRWIAPDGKLvSNTSRTTSYENGTLDLVGTSLGDKGTFTCIASNAAGESTAPVELVV 375
Cdd:cd05745    1 EGQTVDFLCEAQGYPQPVIAWTKGGSQL-SVDRRHLVLSSGTLRISRVALHDQGQYECQAVNIVGSQRTVAQLTV 74

Second C-terminal immunoglobulin (Ig)-like domain of palladin; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the C-terminal immunoglobulin (Ig)-like domain of palladin. Palladin belongs to the palladin-myotilin-myopalladin family. Proteins belonging to this family contain multiple Ig-like domains and function as scaffolds, modulating actin cytoskeleton. Palladin binds to alpha-actinin ezrin, vasodilator-stimulated phosphoprotein VASP, SPIN90 (also known as DIP or mDia interacting protein), and Src. Palladin also binds F-actin directly, via its Ig3 domain. Palladin is expressed as several alternatively spliced isoforms, having various combinations of Ig-like domains, in a cell-type-specific manner. It has been suggested that palladin's different Ig-like domains may be specialized for distinct functions. This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391 297 VAVSEGQSVSLKCKAVGDPDPYVRWiAPDGKLVSNTS--RTTSYENGTLDLV--GTSLGDKGTFTCIASNAAGESTAPVE 372
Cdd:cd20990   10 LTVQEGKLCRMDCKVSGLPTPDLSW-QLDGKPIRPDSahKMLVRENGVHSLIiePVTSRDAGIYTCIATNRAGQNSFNLE 88

                 ...
gi 326936391 373 LVV 375
Cdd:cd20990   89 LVV 91

Second immunoglobulin (Ig)-like domain in Robo (roundabout) receptors; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the second immunoglobulin (Ig)-like domain in Robo (roundabout) receptors. Robo receptors play a role in the development of the central nervous system (CNS), and are receptors of the Slit protein. Slit is a repellant secreted by the neural cells in the midline. Slit acts through Robo to prevent most neurons from crossing the midline from either side. Three mammalian Robo homologs (Robo1, Robo2, and Robo3), and three mammalian Slit homologs (Slit-1,Slit-2, Slit-3), have been identified. Commissural axons, which cross the midline, express low levels of Robo; longitudinal axons, which avoid the midline, express high levels of Robo. Robo1, Robo2, and Robo3 are expressed by commissural neurons in the vertebrate spinal cord and Slit-1, Slit-2, Slit-3 are expressed at the ventral midline. Robo-3 is a divergent member of the Robo family which instead of being a positive regulator of Slit responsiveness, antagonizes Slit responsiveness in precrossing axons. The Slit-Robo interaction is mediated by the second leucine-rich repeat (LRR) domain of Slit and the two N-terminal Ig domains of Robo, Ig1 and Ig2. The primary Robo binding site for Slit-2 has been shown by surface plasmon resonance experiments and mutational analysis to be the Ig1 domain, while the Ig2 domain has been proposed to harbor a weak secondary binding site. This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 326936391 297 VAVSEGQSVSLKCKA-VGDPDPYVRWIAPDGKLVSNTSRTTSYENGTLDLVGTSLGDKGTFTCIASNAAGE-STAPVELV 374
Cdd:cd05724    7 TQVAVGEMAVLECSPpRGHPEPTVSWRKDGQPLNLDNERVRIVDDGNLLIAEARKSDEGTYKCVATNMVGErESRAARLS 86

                 .
gi 326936391 375 V 375
Cdd:cd05724   87 V 87

Fourth immunoglobulin (Ig)-like domain of peroxidasin; The members here are composed of the fourth immunoglobulin (Ig)-like domain in peroxidasin. Peroxidasin has a peroxidase domain and interacting extracellular motifs containing four Ig-like domains. It has been suggested that peroxidasin is secreted, and has functions related to the stabilization of the extracellular matrix. It may play a part in various other important processes such as removal and destruction of cells which have undergone programmed cell death and protection of the organism against non-self.