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 256000817 151 PVLTGTHPVNTTVDFGGTTSFQCKVRSDVKPVIQWLKRVEygsegrhnstidVGGQK--FVVLPTGDVWSRPDG---SYL 225
Cdd:cd04974    1 PILQAGLPANQTVVLGSDVEFHCKVYSDAQPHIQWLKHVE------------VNGSKygPDGLPYVTVLKVAGVnttGEE 68

                         90       100       110
                 ....*....|....*....|....*....|....
gi 256000817 226 NKLLISRARQDDAGMYICLGANTMGYSFRSAFLT 259
Cdd:cd04974   69 NTLTISNVTFDDAGEYICLAGNSIGLSFHSAWLT 102

Third immunoglobulin (Ig)-like domain of fibroblast growth factor receptor (FGFR); member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the third immunoglobulin (Ig)-like domain of fibroblast growth factor receptor (FGFR). Fibroblast growth factors (FGFs) participate in morphogenesis, development, angiogenesis, and wound healing. These FGF-stimulated processes are mediated by four FGFR tyrosine kinases (FGRF1-4). FGFRs are comprised of an extracellular portion consisting of three Ig-like domains, a transmembrane helix, and a cytoplasmic portion having protein tyrosine kinase activity. The highly conserved Ig-like domains 2 and 3, and the linker region between D2 and D3 define a general binding site for FGFs. 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 256000817 151 PVLTGTHPVNTTVDFGGTTSFQCKVRSDVKPVIQWLKRVEygsegrhnstidVGGQK--FVVLPTGDVWSRPDG---SYL 225
Cdd:cd04974    1 PILQAGLPANQTVVLGSDVEFHCKVYSDAQPHIQWLKHVE------------VNGSKygPDGLPYVTVLKVAGVnttGEE 68

                         90       100       110
                 ....*....|....*....|....*....|....
gi 256000817 226 NKLLISRARQDDAGMYICLGANTMGYSFRSAFLT 259
Cdd:cd04974   69 NTLTISNVTFDDAGEYICLAGNSIGLSFHSAWLT 102

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

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 256000817    69 VGSSVRLKCVASGHPRPDIMWMKDDQTL----THLEASeHRKKKWTLSLKNLKPEDSGKYTCRVSNKAGAINATYKVDV 143
Cdd:smart00410   8 EGESVTLSCEASGSPPPEVTWYKQGGKLlaesGRFSVS-RSGSTSTLTISNVTPEDSGTYTCAATNSSGSASSGTTLTV 85

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 256000817  150 KPVLTgTHPVNTTVDFGGTTSFQCKVRSDVKPVIQWLKrveygsegrhnstidvGGQKFVVLPTGDVWSRPDGSYLNkll 229
Cdd:pfam13927   1 KPVIT-VSPSSVTVREGETVTLTCEATGSPPPTITWYK----------------NGEPISSGSTRSRSLSGSNSTLT--- 60

                          90
                  ....*....|....*...
gi 256000817  230 ISRARQDDAGMYICLGAN 247
Cdd:pfam13927  61 ISNVTRSDAGTYTCVASN 78

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        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 256000817  52 PRFTQPSKMRRRVIARPVGSSVRLKCVASGHPRPDIMWMKDDQTL---THLEASEHRKKKWTLSLKNLKPEDSGKYTCRV 128
Cdd:cd05729    1 PRFTDTEKMEEREHALPAANKVRLECGAGGNPMPNITWLKDGKEFkkeHRIGGTKVEEKGWSLIIERAIPRDKGKYTCIV 80

                         90
                 ....*....|....*
gi 256000817 129 SNKAGAINATYKVDV 143
Cdd:cd05729   81 ENEYGSINHTYDVDV 95

Second immunoglobulin (Ig)-like domain of fibroblast growth factor (FGF) receptor; 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.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 256000817  52 PRFTQPSKMRRRVIARPVGSSVRLKCVASGHPRPDIMWMKDDQTLThleaSEHR-------KKKWTLSLKNLKPEDSGKY 124
Cdd:cd05857    1 PYWTNPEKMEKKLHAVPAANTVKFRCPAAGNPTPTMRWLKNGKEFK----QEHRiggykvrNQHWSLIMESVVPSDKGNY 76

                         90
                 ....*....|....*....
gi 256000817 125 TCRVSNKAGAINATYKVDV 143
Cdd:cd05857   77 TCVVENEYGSINHTYHLDV 95

Third immunoglobulin (Ig)-like domain of fibroblast growth factor receptor 2 (FGFR2); member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the third immunoglobulin (Ig)-like domain of human fibroblast growth factor receptor 2 (FGFR2). Fibroblast growth factors (FGFs) participate in morphogenesis, development, angiogenesis, and wound healing. These FGF-stimulated processes are mediated by four FGFR tyrosine kinases (FGRF1-4). FGFRs are comprised of an extracellular portion consisting of three Ig-like domains, a transmembrane helix, and a cytoplasmic portion having protein tyrosine kinase activity. The highly conserved Ig-like domains 2 and 3, and the linker region between D2 and D3 define a general binding site for FGFs. FGFR2 is required for male sex determination. 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 256000817 151 PVLTGTHPVNTTVDFGGTTSFQCKVRSDVKPVIQWLKRVEygsegRHNSTIDVGGQKFV-VLPTGDVwsRPDGSYLNKLL 229
Cdd:cd05858    1 PILQAGLPANTSVVVGTDAEFVCKVYSDAQPHIQWLKHVE-----KNGSKYGPDGLPYVeVLKTAGV--NTTDKEIEVLY 73

                         90       100       110
                 ....*....|....*....|....*....|..
gi 256000817 230 ISRARQDDAGMYICLGANTMGYSFRSAFLTVL 261
Cdd:cd05858   74 LRNVTFEDAGEYTCLAGNSIGISHHSAWLTVL 105

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 256000817   51 RPRFTQPSkmrrRVIARPVGSSVRLKCVASGHPRPDIMWMKDDQTLTHLEASEHRKKKW--TLSLKNLKPEDSGKYTCRV 128
Cdd:pfam13927   1 KPVITVSP----SSVTVREGETVTLTCEATGSPPPTITWYKNGEPISSGSTRSRSLSGSnsTLTISNVTRSDAGTYTCVA 76

                  ..
gi 256000817  129 SN 130
Cdd:pfam13927  77 SN 78

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        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 256000817  52 PRFTQ-PSKmrrrVIARPVGSSVRLKCVASGHPRPDIMWMKDDQTLThlEASEHRK-KKWTLSLKNLKPEDSGKYTCRVS 129
Cdd:cd20978    1 PKFIQkPEK----NVVVKGGQDVTLPCQVTGVPQPKITWLHNGKPLQ--GPMERATvEDGTLTIINVQPEDTGYYGCVAT 74

                         90
                 ....*....|....
gi 256000817 130 NKAGAINATYKVDV 143
Cdd:cd20978   75 NEIGDIYTETLLHV 88

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
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 256000817  68 PVGSSVRLKCVASGHPRPDIMWMKDDQTLT---HLEASEHRKKKWTLSLKNLKPEDSGKYTCRVSNKAGAINATYKVDV 143
Cdd:cd20973   10 VEGSAARFDCKVEGYPDPEVKWMKDDNPIVesrRFQIDQDEDGLCSLIISDVCGDDSGKYTCKAVNSLGEATCSAELTV 88

Immunoglobulin (Ig)-like domain of titin and similar proteins; The members here are composed of the immunoglobulin (Ig)-like domain found in titin-like proteins and similar proteins. Titin (also called connectin) is a fibrous sarcomeric protein specifically found in vertebrate striated muscle. Titin is a giant protein; 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. It appears to function similarly to an elastic band, keeping the myosin filaments centered in the sarcomere during muscle contraction or stretching. Within the sarcomere, titin is also attached to or is associated with myosin binding protein C (MyBP-C). MyBP-C appears to contribute to the generation of passive tension by titin and like titin has repeated Ig-like and FN-III domains. Also included in this group are worm twitchin and insect projectin, thick filament proteins of invertebrate muscle which also have repeated Ig-like and FN-III domains.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 256000817  63 RVIARpVGSSVRLKCVASGHPRPDIMWMKDDQTLT-----HLEASEHRKkkwTLSLKNLKPEDSGKYTCRVSNKAGAINA 137
Cdd:cd05748    1 TIVVR-AGESLRLDIPIKGRPTPTVTWSKDGQPLKetgrvQIETTASST---SLVIKNAKRSDSGKYTLTLKNSAGEKSA 76

                 ....*.
gi 256000817 138 TYKVDV 143
Cdd:cd05748   77 TINVKV 82

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 256000817  70 GSSVRLKCVASGHPRPDIMWMKDDQTLTHLE-------ASEHRKKKWTLSLKNLKPEDSGKYTCRVSNKAGAINATYKVD 142
Cdd:cd20956   16 GPSVSLKCVASGNPLPQITWTLDGFPIPESPrfrvgdyVTSDGDVVSYVNISSVRVEDGGEYTCTATNDVGSVSHSARIN 95

                 .
gi 256000817 143 V 143
Cdd:cd20956   96 V 96

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 256000817  69 VGSSVRLKCVASGHPRPDIMWMKD-------DQTLTHLEASehrkkkwTLSLKNLKPEDSGKYTCRVSNKAGAINATYKV 141
Cdd:cd20952   13 VGGTVVLNCQATGEPVPTISWLKDgvpllgkDERITTLENG-------SLQIKGAEKSDTGEYTCVALNLSGEATWSAVL 85

                 ..
gi 256000817 142 DV 143
Cdd:cd20952   86 DV 87

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 256000817 158 PVNTTVDFGGTTSFQCKVRSDVKPVIQWLKrveygsEGRhnsTIDVGGQKFVVLPTGdvwsrpdgsylnKLLISRARQDD 237
Cdd:cd20952    6 PQNQTVAVGGTVVLNCQATGEPVPTISWLK------DGV---PLLGKDERITTLENG------------SLQIKGAEKSD 64

                         90       100
                 ....*....|....*....|...
gi 256000817 238 AGMYICLGANTMGYSFRSAFLTV 260
Cdd:cd20952   65 TGEYTCVALNLSGEATWSAVLDV 87

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 256000817  52 PRFTQpsKMRRRVIARpvGSSVRLKCVASGHPRPDIMWMKDDQTL-------THLEASEHrkkkwTLSLKNLKPEDSGKY 124
Cdd:cd20972    2 PQFIQ--KLRSQEVAE--GSKVRLECRVTGNPTPVVRWFCEGKELqnspdiqIHQEGDLH-----SLIIAEAFEEDTGRY 72

                         90
                 ....*....|....*....
gi 256000817 125 TCRVSNKAGAINATYKVDV 143
Cdd:cd20972   73 SCLATNSVGSDTTSAEIFV 91

Immunoglobulin domain; Members of the immunoglobulin superfamily are found in hundreds of proteins of different functions. Examples include antibodies, the giant muscle kinase titin and receptor tyrosine kinases. Immunoglobulin-like domains may be involved in protein-protein and protein-ligand interactions.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 256000817   68 PVGSSVRLKC-VASGHPRPDIMWMKDDQTLTHLEASEH---RKKKWTLSLKNLKPEDSGKYTCRVSNKAGAINATYKV 141
Cdd:pfam00047   9 LEGDSATLTCsASTGSPGPDVTWSKEGGTLIESLKVKHdngRTTQSSLLISNVTKEDAGTYTCVVNNPGGSATLSTSL 86

Fourth Ig-like domain from smooth muscle myosin light chain kinase and similar domains ; a member of the I-set of IgSF domains; The members here are composed of the fourth immunoglobulin (Ig)-like domain from smooth muscle myosin light chain kinase (MYLK) and similar domains. 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 this group shows that the fourth Ig-like domain from myosin light chain kinase lacks this strand and thus 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
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 256000817  70 GSSVRLKCVASGHPRPDIMWMKDDQTLTHLEA-SEHRKKKWTLSLKNLKPEDSGKYTCRVSNKAGAINATYKVDV 143
Cdd:cd20976   16 GQDFVAQCSARGKPVPRITWIRNAQPLQYAADrSTCEAGVGELHIQDVLPEDHGTYTCLAKNAAGQVSCSAWVTV 90

C-terminal immunoglobulin (Ig)-like domain of myomesin and M-protein; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the C-terminal immunoglobulin (Ig)-like domain of myomesin and M-protein (also known as myomesin-2). Myomesin and M-protein are both structural proteins localized to the M-band, a transverse structure in the center of the sarcomere, and are candidates for M-band bridges. Both proteins are modular, consisting mainly of repetitive Ig-like and fibronectin type III (FnIII) domains. Myomesin is expressed in all types of vertebrate striated muscle; M-protein has a muscle-type specific expression pattern. Myomesin is present in both slow and fast fibers; M-protein is present only in fast fibers. It has been suggested that myomesin acts as a molecular spring with alternative splicing as a means of modifying its elasticity.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 256000817  70 GSSVRLKCVASGHPRPDIMWMKDDQTLT---HLEASEHRKKKWTLSLKNLKPEDSGKYTCRVSNKAGAINATYKVDV 143
Cdd:cd05737   16 GKTLNLTCNVWGDPPPEVSWLKNDQALAfldHCNLKVEAGRTVYFTINGVSSEDSGKYGLVVKNKYGSETSDVTVSV 92

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 256000817  56 QPSKMRrrVIarpVGSSVRLKCVAS-GHPRPDIMWMKDDQTLTHLEASEHRKKKWTLSLKNLKPEDSGKYTCRVSNKAGA 134
Cdd:cd05724    3 EPSDTQ--VA---VGEMAVLECSPPrGHPEPTVSWRKDGQPLNLDNERVRIVDDGNLLIAEARKSDEGTYKCVATNMVGE 77

Third 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 third 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 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, 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, and 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 Slit2 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 256000817 158 PVNTTVDFGGTTSFQCKVRSDVKPVIQWLKrveygSEGRhnstidvggqkfvvLPTGDVWSRPDGSylnkLLISRARQDD 237
Cdd:cd05725    4 PQNQVVLVDDSAEFQCEVGGDPVPTVRWRK-----EDGE--------------LPKGRYEILDDHS----LKIRKVTAGD 60

                         90       100
                 ....*....|....*....|...
gi 256000817 238 AGMYICLGANTMGYSFRSAFLTV 260
Cdd:cd05725   61 MGSYTCVAENMVGKIEASATLTV 83

Fourth immunoglobulin (Ig)-like domain of L1, Ng-CAM (Neuron-glia CAM cell adhesion molecule), and NrCAM (Ng-CAM-related); The members here are composed of the fourth immunoglobulin (Ig)-like domain of L1, Ng-CAM (Neuron-glia CAM cell adhesion molecule), and NrCAM (Ng-CAM-related). These proteins belong to the L1 subfamily of cell adhesion molecules (CAMs) and are comprised of an extracellular region having six Ig-like domains and five fibronectin type III domains, a transmembrane region and an intracellular domain. These molecules are primarily expressed in the nervous system. L1 is associated with an X-linked recessive disorder, X-linked hydrocephalus, MASA syndrome, or spastic paraplegia type 1, that involves abnormalities of axonal growth.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 256000817  70 GSSVRLKCVASGHPRPDIMWMKDDQTLTHLEASEHRK-KKWTLSLKNLKPEDSGKYTCRVSNKAGAINATYKVDVI 144
Cdd:cd04978   14 GETGELICEAEGNPQPTITWRLNGVPIEPAPEDMRRTvDGRTLIFSNLQPNDTAVYQCNASNVHGYLLANAFLHVL 89

Immunoglobulin I-set domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 256000817  151 PVLTgTHPVNTTVDFGGTTSFQCKVRSDVKPVIQWLKRveyGSEGRhnstidvGGQKFVVLPTGDVWSrpdgsylnkLLI 230
Cdd:pfam07679   1 PKFT-QKPKDVEVQEGESARFTCTVTGTPDPEVSWFKD---GQPLR-------SSDRFKVTYEGGTYT---------LTI 60

                          90       100       110
                  ....*....|....*....|....*....|
gi 256000817  231 SRARQDDAGMYICLGANTMGYSFRSAFLTV 260
Cdd:pfam07679  61 SNVQPDDSGKYTCVATNSAGEAEASAELTV 90

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
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 256000817  70 GSSVRLKCVASGHPRPDIMWMKDDQTLThlEASEHRK-----KKWTLSLKNLKPEDSGKYTCRVSNKAGAINATYKVDV 143
Cdd:cd05744   15 GRLCRFDCKVSGLPTPDLFWQLNGKPVR--PDSAHKMlvrenGRHSLIIEPVTKRDAGIYTCIARNRAGENSFNAELVV 91

Third immunoglobulin domain of the Drosophila melanogaster Dscam protein, and similar domains; a member of the Constant 2 (C2)-set of IgSF domains; The members here are composed of the third 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. 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. This group belongs to the C2-set of IgSF domains, having A, B, and E strands in one beta-sheet and A', G, F, C, and C' in the other. Unlike other Ig domain sets, the C2-set lacks the D strand.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 256000817  69 VGSSVRLKCVASGHPRPDIMWMKDDQTLTHlEASEHRKKKWTLSLKNLKPEDSGKYTCRVSNKAGAINAT 138
Cdd:cd20957   15 FGRTAVFNCSVTGNPIHTVLWMKDGKPLGH-SSRVQILSEDVLVIPSVKREDKGMYQCFVRNDGDSAQAT 83

Second immunoglobulin (Ig)-like domain of protein tyrosine kinase (PTK) 7; The members here are composed of the second immunoglobulin (Ig)-like domain in protein tyrosine kinase (PTK) 7, also known as CCK4. PTK7 is a subfamily of the receptor protein tyrosine kinase family, and is referred to as an RPTK-like molecule. RPTKs transduce extracellular signals across the cell membrane and play important roles in regulating cell proliferation, migration, and differentiation. PTK7 is organized as an extracellular portion having seven Ig-like domains, a single transmembrane region, and a cytoplasmic tyrosine kinase-like domain. PTK7 is considered a pseudokinase as it has several unusual residues in some of the highly conserved tyrosine kinase (TK) motifs; it is predicted to lack TK activity. PTK7 may function as a cell-adhesion molecule. PTK7 mRNA is expressed at high levels in placenta, melanocytes, liver, lung, pancreas, and kidney. PTK7 is overexpressed in several cancers, including melanoma and colon cancer lines.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 256000817  71 SSVRLKCVASGHPRPDIMWMKDDQTL-----THLEASEHRkkkwTLSLKNLKPEDSGKYTCRVSNKAGAI 135
Cdd:cd05760   17 SRVTLRCHIDGHPRPTYQWFRDGTPLsdgqgNYSVSSKER----TLTLRSAGPDDSGLYYCCAHNAFGSV 82

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.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 256000817  73 VRLKCVASGHPRPDIMWMKDDQTLTHlEASEHRKKKWTLSLKNLKPEDSGKYTCRVSNKAG 133
Cdd:cd05746    1 VQIPCSAQGDPEPTITWNKDGVQVTE-SGKFHISPEGYLAIRDVGVADQGRYECVARNTIG 60

Fifth immunoglobulin (Ig) domain of contactin; The members here are composed of the fifth immunoglobulin (Ig) domain of contactins. Contactins are neural cell adhesion molecules and are comprised of six Ig domains followed by four fibronectin type III (FnIII) domains anchored to the membrane by glycosylphosphatidylinositol. The first four Ig domains form the intermolecular binding fragment, which arranges as a compact U-shaped module via contacts between Ig domains 1 and 4, and between Ig domains 2 and 3. Contactin-2 (TAG-1, axonin-1) may play a part in the neuronal processes of neurite outgrowth, axon guidance and fasciculation, and neuronal migration. This group also includes contactin-1 and contactin-5. The different contactins show different expression patterns in the central nervous system. During development and in adulthood, contactin-2 is transiently expressed in subsets of central and peripheral neurons. Contactin-5 is expressed specifically in the rat postnatal nervous system, peaking at about 3 weeks postnatal, and a lack of contactin-5 (NB-2) results in an impairment of neuronal activity in the rat auditory system. Contactin-5 is highly expressed in the adult human brain in the occipital lobe and in the amygdala. Contactin-1 is differentially expressed in tumor tissues and may, through a RhoA mechanism, facilitate invasion and metastasis of human lung adenocarcinoma.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 256000817  62 RRVIARPVGSSVRLKCVASGHPRPDIMWMKDDQTLThlEASE-HRKKKWTLSLKNLKPEDSGKYTCRVSNKAGAINATYK 140
Cdd:cd04969    9 KKKILAAKGGDVIIECKPKASPKPTISWSKGTELLT--NSSRiCILPDGSLKIKNVTKSDEGKYTCFAVNFFGKANSTGS 86

                 ...
gi 256000817 141 VDV 143
Cdd:cd04969   87 LSV 89

First immunoglobulin (Ig)-like constant domain in Robo (roundabout) receptors, and similar domains; The members here are composed of the first immunoglobulin (Ig)-like domain in Roundabout (Robo) receptors. 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, Robo2, and Robo3), and three mammalian Slit homologs (Slit1, Slit2, Slit3), 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 Slit1, Slit2,and Slit3 are expressed at the ventral midline. Robo3 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.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 256000817 157 HPVNTTVDFGGTTSFQCKVRSDVKPVIQWLKrveyGSEGRHNSTIDVGGQKfVVLPTGdvwsrpdGSYLNKLLISRARQD 236
Cdd:cd07693    6 HPSDLIVSKGDPATLNCKAEGRPTPTIQWLK----NGQPLETDKDDPRSHR-IVLPSG-------SLFFLRVVHGRKGRS 73

                         90       100
                 ....*....|....*....|....*
gi 256000817 237 DAGMYICLGANTMGYSF-RSAFLTV 260
Cdd:cd07693   74 DEGVYVCVAHNSLGEAVsRNASLEV 98

Immunoglobulin (Ig)-like domain of Down Syndrome Cell Adhesion molecule (DSCAM); The members here are composed of the immunoglobulin (Ig)-like domain of Down Syndrome Cell Adhesion molecule (DSCAM). DSCAM is a cell adhesion molecule expressed largely in the developing nervous system. The gene encoding DSCAM is located at human chromosome 21q22, the locus associated with the intellectual disability phenotype of Down Syndrome. DSCAM is predicted to be the largest member of the IG superfamily. It has been demonstrated that DSCAM can mediate cation-independent homophilic intercellular adhesion.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 256000817  70 GSSVRLKCVASGHPRPDIMWM----KDDQTLTHLEASEHRKK---KWTLSLKNLKPEDSGKYTCRVSNKAGA 134
Cdd:cd05734   16 GKAVVLNCSADGYPPPTIVWKhskgSGVPQFQHIVPLNGRIQllsNGSLLIKHVLEEDSGYYLCKVSNDVGA 87

Fourth immunoglobulin (Ig)-like domain in Robo (roundabout) receptors; member of the I-set of Ig superfamily (IgSF) domains; Members here are composed the fourth 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 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, 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, and 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 Slit2 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 256000817 156 THPVNTTVDFGGTTSFQCKVRSDVKPVIQWLKrveygsEGRHNSTIDVGGQ----KFVVLPTGDvwsrpdgsylnkLLIS 231
Cdd:cd05726    4 VKPRDQVVALGRTVTFQCETKGNPQPAIFWQK------EGSQNLLFPYQPPqpssRFSVSPTGD------------LTIT 65

                         90       100
                 ....*....|....*....|....*....
gi 256000817 232 RARQDDAGMYICLGANTMGYSFRSAFLTV 260
Cdd:cd05726   66 NVQRSDVGYYICQALNVAGSILAKAQLEV 94

Third immunoglobulin (Ig) domain of contactin-1; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the third immunoglobulin (Ig) domain of the neural cell adhesion molecule contactin-1. Contactins are comprised of six Ig domains followed by four fibronectin type III (FnIII) domains anchored to the membrane by glycosylphosphatidylinositol. Contactin-1 is differentially expressed in tumor tissues and may through a RhoA mechanism, facilitate invasion and metastasis of human lung adenocarcinoma. This group belongs to the I-set of IgSF domains.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 256000817  70 GSSVRLKCVASGHPRPDIMWMKDDQTLThlEASEHRKKKWTLSLKNLKPEDSGKYTCRVSNKAG 133
Cdd:cd05851   16 GQNVTLECFALGNPVPVIRWRKILEPMP--ATAEISMSGAVLKIFNIQPEDEGTYECEAENIKG 77