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 768006403 283 PQVVPSSLNLVENARSVDLTCQTVNQSVNVQWFLSGQPLLPSEHLQLSADNRTLIIHGLQRNDTGPYACEVWNWGSRARS 362
Cdd:cd05740    2 PFISSNNSNPVEDKDAVTLTCEPETQNTSYLWWFNGQSLPVTPRLTLSNGNRTLTLLNVTREDAGAYQCEISNPVSANRS 81

                 ....*...
gi 768006403 363 EPLELTIN 370
Cdd:cd05740   82 DPVTLDVI 89

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
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 768006403 396 SSLTLQCWAESKPGAEYRWTLeHSTGEHLGEQLIIRALTWEHDGIYNCTASNSLTGLARSTSVLVKV 462
Cdd:cd20948   11 ENLNLSCHAASNPPAQYSWTI-NGTFQTSSQELFLPAITENNEGTYTCSAHNSLTGKNISLVLSVTV 76

Immunoglobulin (Ig)-like domain of human carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) domains 2, 4, and 6, and similar domains; The members here are composed of the second, fourth, and sixth immunoglobulin (Ig)-like domains in human carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) protein subfamily. The CEA family is a group of anchored or secreted glycoproteins expressed by epithelial cells, leukocytes, endothelial cells, and placenta. The CEA family is divided into the CEACAM and pregnancy-specific glycoprotein (PSG) subfamilies. This group represents the CEACAM subfamily. CEACAM1 has many important cellular functions; it is a cell adhesion molecule and a signaling molecule that regulates the growth of tumor cells, an angiogenic factor, and a receptor for bacterial and viral pathogens, including mouse hepatitis virus (MHV). In mice, four isoforms of CEACAM1 generated by alternative splicing have either two [D1, D4] or four [D1-D4] Ig-like domains on the cell surface.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 768006403 283 PQVVPSSLNLVENARSVDLTCQTVNQSVNVQWFLSGQPLLPSEHLQLSADNRTLIIHGLQRNDTGPYACEVWNWGSRARS 362
Cdd:cd05740    2 PFISSNNSNPVEDKDAVTLTCEPETQNTSYLWWFNGQSLPVTPRLTLSNGNRTLTLLNVTREDAGAYQCEISNPVSANRS 81

                 ....*...
gi 768006403 363 EPLELTIN 370
Cdd:cd05740   82 DPVTLDVI 89

Fifth immunoglobulin (Ig)-like domain of the carcinoembryonic antigen (CEA) related cell adhesion molecule 5 (CEACAM5) and similar domains; member of the C2-set IgSF domains; The members here are composed of the fifth immunoglobulin (Ig)-like domain of the carcinoembryonic antigen (CEA) related cell adhesion molecule 5 (CEACAM5) and similar domains. The CEA family is a group of anchored or secreted glycoproteins, expressed by epithelial cells, leukocytes, endothelial cells and placenta. The CEA family is divided into the CEACAM and pregnancy-specific glycoprotein (PSG) subfamilies. Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5), also known as CD66e (Cluster of Differentiation 66e), is a cell surface glycoprotein that plays a role in cell adhesion, intracellular signaling and tumor progression. Diseases associated with CEACAM5 include lung cancer and rectum cancer. 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' in the other. Unlike other Ig domain sets, the C2-set lacks the D strand.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 768006403 396 SSLTLQCWAESKPGAEYRWTLeHSTGEHLGEQLIIRALTWEHDGIYNCTASNSLTGLARSTSVLVKV 462
Cdd:cd20948   11 ENLNLSCHAASNPPAQYSWTI-NGTFQTSSQELFLPAITENNEGTYTCSAHNSLTGKNISLVLSVTV 76

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

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 768006403    97 PSIAVSPGtaieqkDMVTFYCTTK-DVNITIHWVSNNLSIVFH-ERMQLSKDGKILTILI--VQREDSGTYQCEARDA 170
Cdd:smart00410   2 PSVTVKEG------ESVTLSCEASgSPPPEVTWYKQGGKLLAEsGRFSVSRSGSTSTLTIsnVTPEDSGTYTCAATNS 73

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

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 768006403   202 EVVEVMEGSSMTFLAETKSHPPCAYTWFLLDSIL-----------SHTTRTFTIHAVSREHEGLYRCLVSNSATHLSSLG 270
Cdd:smart00410   2 PSVTVKEGESVTLSCEASGSPPPEVTWYKQGGKLlaesgrfsvsrSGSTSTLTISNVTPEDSGTYTCAATNSSGSASSGT 81

                   ....
gi 768006403   271 TLKV 274
Cdd:smart00410  82 TLTV 85

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 768006403  198 VASGEVVEVMEGSSMTFLAETKSHPPCAYTWFLLDSILSH----------TTRTFTIHAVSREHEGLYRCLVSN 261
Cdd:pfam13927   5 TVSPSSVTVREGETVTLTCEATGSPPPTITWYKNGEPISSgstrsrslsgSNSTLTISNVTRSDAGTYTCVASN 78

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

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 768006403   298 SVDLTCQ-TVNQSVNVQWFLSG-QPLLPSEHLQLSADNR--TLIIHGLQRNDTGPYACEVWNwGSRARSEPLELTI 369
Cdd:smart00410  11 SVTLSCEaSGSPPPEVTWYKQGgKLLAESGRFSVSRSGStsTLTISNVTPEDSGTYTCAATN-SSGSASSGTTLTV 85

IL-1 receptor-like protein; Provisional

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 768006403 244 IHAVSREHEGLYRCLVSNSatHLSSLGTLKVRVLETLTMPQVvpsslnlvENARSVDLTC------QTVNQSVNVQWFLS 317
Cdd:PHA02826 102 IGNVINIDEGIYICTISSG--NICEESTIRLTFDSGTINYQF--------NSGKDSKLHCygtdgiSSTFKDYTLTWYKN 171

                         90       100       110       120       130       140
                 ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 768006403 318 GQPLLPSEHLQLSADNRTLIIHGLQRNDTGPYACevwnwgsrarseplELTINYGPDQVHITRE 381
Cdd:PHA02826 172 GNIVLYTDRIQLRNNNSTLVIKSATHDDSGIYTC--------------NLRFNKNSNNYNITKE 221

Immunoglobulin (Ig)-like domain of human carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) domains 2, 4, and 6, and similar domains; The members here are composed of the second, fourth, and sixth immunoglobulin (Ig)-like domains in human carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) protein subfamily. The CEA family is a group of anchored or secreted glycoproteins expressed by epithelial cells, leukocytes, endothelial cells, and placenta. The CEA family is divided into the CEACAM and pregnancy-specific glycoprotein (PSG) subfamilies. This group represents the CEACAM subfamily. CEACAM1 has many important cellular functions; it is a cell adhesion molecule and a signaling molecule that regulates the growth of tumor cells, an angiogenic factor, and a receptor for bacterial and viral pathogens, including mouse hepatitis virus (MHV). In mice, four isoforms of CEACAM1 generated by alternative splicing have either two [D1, D4] or four [D1-D4] Ig-like domains on the cell surface.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 768006403 283 PQVVPSSLNLVENARSVDLTCQTVNQSVNVQWFLSGQPLLPSEHLQLSADNRTLIIHGLQRNDTGPYACEVWNWGSRARS 362
Cdd:cd05740    2 PFISSNNSNPVEDKDAVTLTCEPETQNTSYLWWFNGQSLPVTPRLTLSNGNRTLTLLNVTREDAGAYQCEISNPVSANRS 81

                 ....*...
gi 768006403 363 EPLELTIN 370
Cdd:cd05740   82 DPVTLDVI 89

Fifth immunoglobulin (Ig)-like domain of the carcinoembryonic antigen (CEA) related cell adhesion molecule 5 (CEACAM5) and similar domains; member of the C2-set IgSF domains; The members here are composed of the fifth immunoglobulin (Ig)-like domain of the carcinoembryonic antigen (CEA) related cell adhesion molecule 5 (CEACAM5) and similar domains. The CEA family is a group of anchored or secreted glycoproteins, expressed by epithelial cells, leukocytes, endothelial cells and placenta. The CEA family is divided into the CEACAM and pregnancy-specific glycoprotein (PSG) subfamilies. Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5), also known as CD66e (Cluster of Differentiation 66e), is a cell surface glycoprotein that plays a role in cell adhesion, intracellular signaling and tumor progression. Diseases associated with CEACAM5 include lung cancer and rectum cancer. 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' in the other. Unlike other Ig domain sets, the C2-set lacks the D strand.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 768006403 396 SSLTLQCWAESKPGAEYRWTLeHSTGEHLGEQLIIRALTWEHDGIYNCTASNSLTGLARSTSVLVKV 462
Cdd:cd20948   11 ENLNLSCHAASNPPAQYSWTI-NGTFQTSSQELFLPAITENNEGTYTCSAHNSLTGKNISLVLSVTV 76

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

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 768006403    97 PSIAVSPGtaieqkDMVTFYCTTK-DVNITIHWVSNNLSIVFH-ERMQLSKDGKILTILI--VQREDSGTYQCEARDA 170
Cdd:smart00410   2 PSVTVKEG------ESVTLSCEASgSPPPEVTWYKQGGKLLAEsGRFSVSRSGSTSTLTIsnVTPEDSGTYTCAATNS 73

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

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 768006403   202 EVVEVMEGSSMTFLAETKSHPPCAYTWFLLDSIL-----------SHTTRTFTIHAVSREHEGLYRCLVSNSATHLSSLG 270
Cdd:smart00410   2 PSVTVKEGESVTLSCEASGSPPPEVTWYKQGGKLlaesgrfsvsrSGSTSTLTISNVTPEDSGTYTCAATNSSGSASSGT 81

                   ....
gi 768006403   271 TLKV 274
Cdd:smart00410  82 TLTV 85

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 768006403  198 VASGEVVEVMEGSSMTFLAETKSHPPCAYTWFLLDSILSH----------TTRTFTIHAVSREHEGLYRCLVSN 261
Cdd:pfam13927   5 TVSPSSVTVREGETVTLTCEATGSPPPTITWYKNGEPISSgstrsrslsgSNSTLTISNVTRSDAGTYTCVASN 78

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 768006403  388 STIEAELNSSLTLQCWAESKPGAEYRWT--------LEHSTGEHLGEQ--LIIRALTWEHDGIYNCTASN 447
Cdd:pfam13927   9 SSVTVREGETVTLTCEATGSPPPTITWYkngepissGSTRSRSLSGSNstLTISNVTRSDAGTYTCVASN 78

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
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 768006403 299 VDLTCQTV-NQSVNVQWFLSGQPLLPSEHL--QLSADNRTLIIHGLQRNDTGPYACEVWNWGSRARS 362
Cdd:cd00096    1 VTLTCSASgNPPPTITWYKNGKPLPPSSRDsrRSELGNGTLTISNVTLEDSGTYTCVASNSAGGSAS 67

Immunoglobulin domain; This domain contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 768006403   96 KPSIAVSPgTAIEQKDMVTFYCTTK-DVNITIHWVSNNLSIvfhermqlsKDGKILTILIVQREDSGTYQCEARDALLSQ 174
Cdd:pfam13895   1 KPVLTPSP-TVVTEGEPVTLTCSAPgNPPPSYTWYKDGSAI---------SSSPNFFTLSVSAEDSGTYTCVARNGRGGK 70

                  ....*....
gi 768006403  175 RSDPIFLDV 183
Cdd:pfam13895  71 VSNPVELTV 79

Immunoglobulin domain; This domain contains immunoglobulin-like domains.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 768006403  396 SSLTLQCWAESKPGAEYRWTLEhstGEHLGEQ--LIIRALTWEHDGIYNCTASNSLTGLaRSTSVLVKV 462
Cdd:pfam13895  15 EPVTLTCSAPGNPPPSYTWYKD---GSAISSSpnFFTLSVSAEDSGTYTCVARNGRGGK-VSNPVELTV 79

Fifth 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 fifth 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
                 ....*....|....*....|....*....|....*....|....*.
gi 768006403 311 NVQWFLSGQPLlPSEHLQLSADNRTLIIHGLQRN-DTGPYACEVWN 355
Cdd:cd20958   31 SITWEKDGRRL-PLNHRQRVFPNGTLVIENVQRSsDEGEYTCTARN 75

agrin-responsive first immunoglobulin-like domains (Ig1) of the MuSK ectodomain; a member of the I-set of IgSF domains; The members here are composed of the first immunoglobulin-like domains (Ig1) of the Muscle-specific kinase (MuSK). MuSK is a receptor tyrosine kinase specifically expressed in skeletal muscle, where it plays a central role in the formation and maintenance of the neuromuscular junction (NMJ). MuSK is activated by agrin, a neuron-derived heparan sulfate proteoglycan. The activation of MUSK in myotubes regulates the formation of NMJs through the regulation of different processes including the specific expression of genes in subsynaptic nuclei, the reorganization of the actin cytoskeleton and the clustering of the acetylcholine receptors (AChR) in the postsynaptic membrane. 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 MuSK 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 768006403 382 SASEMISTIEAELNSSLTLQCWAESKPGAEYRWT------LEHSTGEHL---GEQLIIRALTWEHDGIYNCTASNSLTG 451
Cdd:cd20970    4 STPQPSFTVTAREGENATFMCRAEGSPEPEISWTrngnliIEFNTRYIVrenGTTLTIRNIRRSDMGIYLCIASNGVPG 82

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        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 768006403 287 PSSLNLVENARSVD------LTCQ-TVNQSVNVQWFLSGQPLLPSEHLQLSADNRtLIIHGLQRNDTGPYACEVWNWGSR 359
Cdd:cd20957    1 PLSATIDPPVQTVDfgrtavFNCSvTGNPIHTVLWMKDGKPLGHSSRVQILSEDV-LVIPSVKREDKGMYQCFVRNDGDS 79

                 ...
gi 768006403 360 ARS 362
Cdd:cd20957   80 AQA 82

Fifth immunoglobulin (Ig)-like domain of the carcinoembryonic antigen (CEA) related cell adhesion molecule 5 (CEACAM5) and similar domains; member of the C2-set IgSF domains; The members here are composed of the fifth immunoglobulin (Ig)-like domain of the carcinoembryonic antigen (CEA) related cell adhesion molecule 5 (CEACAM5) and similar domains. The CEA family is a group of anchored or secreted glycoproteins, expressed by epithelial cells, leukocytes, endothelial cells and placenta. The CEA family is divided into the CEACAM and pregnancy-specific glycoprotein (PSG) subfamilies. Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5), also known as CD66e (Cluster of Differentiation 66e), is a cell surface glycoprotein that plays a role in cell adhesion, intracellular signaling and tumor progression. Diseases associated with CEACAM5 include lung cancer and rectum cancer. 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' in the other. Unlike other Ig domain sets, the C2-set lacks the D strand.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 768006403 208 EGSSMTFLAETKSHPPCAYTWFLLDSILSHTTRTFtIHAVSREHEGLYRCLVSNSATHLSSLGTLKVRV 276
Cdd:cd20948    9 SGENLNLSCHAASNPPAQYSWTINGTFQTSSQELF-LPAITENNEGTYTCSAHNSLTGKNISLVLSVTV 76

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
                 ....*....|....*....|....*....|....*....|....*....|...
gi 768006403 226 YTWFLLDSILSHTTR----------TFTIHAVSREHEGLYRCLVSNSATHLSS 268
Cdd:cd00096   15 ITWYKNGKPLPPSSRdsrrselgngTLTISNVTLEDSGTYTCVASNSAGGSAS 67

Immunoglobulin (Ig)-like domain found in Leukocyte Ig-like receptors, Natural killer inhibitory receptors (KIRs) and similar domains; member of Immunoglobulin Constant-2 set of IgSF domains; The members here are composed of the first and second immunoglobulin (Ig)-like domains found in Leukocyte Ig-like receptors (LILRs), Natural killer inhibitory receptors (KIRs, also known as also known as cluster of differentiation (CD) 158), and similar proteins. This group includes LILRB1 (also known as LIR-1), LILRA5 (also known as LIR9), an activating natural cytotoxicity receptor NKp46, the immune-type receptor glycoprotein VI (GPVI), and the IgA-specific receptor Fc-alphaRI (also known as cluster of differentiation (CD) 89). LILRs are a family of immunoreceptors expressed on expressed on T and B cells, on monocytes, dendritic cells, and subgroups of natural killer (NK) cells. The human LILR family contains nine proteins (LILRA1-3, and 5, and LILRB1-5). From functional assays, and as the cytoplasmic domains of various LILRs, for example LILRB1, LILRB2 (also known as LIR-2), and LILRB3 (also known as LIR-3) contain immunoreceptor tyrosine-based inhibitory motifs (ITIMs), it is thought that LIR proteins are inhibitory receptors. Of the eight LIR family proteins, only LILRB1, and LILRB2, show detectable binding to class I MHC molecules; ligands for the other members have yet to be determined. The extracellular portions of the different LIR proteins contain different numbers of Ig-like domains for example, four in the case of LILRB1, and LILRB2, and two in the case of LILRB4 (also known as LIR-5). The activating natural cytotoxicity receptor NKp46 is expressed in natural killer cells, and is organized as an extracellular portion having two Ig-like extracellular domains, a transmembrane domain, and a small cytoplasmic portion. GPVI, which also contains two Ig-like domains, participates in the processes of collagen-mediated platelet activation and arterial thrombus formation. Fc-alphaRI is expressed on monocytes, eosinophils, neutrophils, and macrophages; it mediates IgA-induced immune effector responses such as phagocytosis, antibody-dependent cell-mediated cytotoxicity and respiratory burst. Killer cell immunoglobulin-like receptors (KIRs; also known as CD158 for human KIR) are transmembrane glycoproteins expressed by natural killer cells and subsets of T cells. KIRs are a family of highly polymorphic activating and inhibitory receptors that serve as key regulators of human NK cell function. The KIR proteins are classified by the number of extracellular immunoglobulin domains (2D or 3D) and by whether they have a long (L) or short (S) cytoplasmic domain. KIR proteins with the long cytoplasmic domain transduce inhibitory signals upon ligand binding via an immune tyrosine-based inhibitory motif (ITIM), while KIR proteins with the short cytoplasmic domain lack the ITIM motif and instead associate with the TYRO protein tyrosine kinase binding protein to transduce activating signals. The major ligands for KIR are MHC class I (HLA-A, -B or -C) molecules.

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                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 768006403 284 QVVPSSLnlVENARSVDLTCQTVNQSVNVQWFLSGQPllPSEHLQLSADNRT---LIIHGLQRNDTGPYACEVWNWGSRA 360
Cdd:cd16843    5 SAEPSSV--VPLGENVTIRCQGPPEAVLFQLYKEGNS--LSQGTVREKEPQNkaeFYIPHMDRNHAGRYRCRYRSGTLWS 80

                         90
                 ....*....|
gi 768006403 361 R-SEPLELTI 369
Cdd:cd16843   81 EpSDPLELVV 90

Immunoglobulin domain; This domain contains immunoglobulin-like domains.

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 768006403  283 PQVVPSSLNLVENaRSVDLTCQT-VNQSVNVQWFLSGQPLLPSehlqlsadnRTLIIHGLQRNDTGPYACEVWNWGSRAR 361
Cdd:pfam13895   2 PVLTPSPTVVTEG-EPVTLTCSApGNPPPSYTWYKDGSAISSS---------PNFFTLSVSAEDSGTYTCVARNGRGGKV 71

                  ....*...
gi 768006403  362 SEPLELTI 369
Cdd:pfam13895  72 SNPVELTV 79

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.

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 768006403  388 STIEAELNSSLTLQCWA-ESKPGAEYRWTLE-----------HSTGEHLGEQLIIRALTWEHDGIYNCTASNSLTGLARS 455
Cdd:pfam00047   4 PTVTVLEGDSATLTCSAsTGSPGPDVTWSKEggtlieslkvkHDNGRTTQSSLLISNVTKEDAGTYTCVVNNPGGSATLS 83

                  ...
gi 768006403  456 TSV 458
Cdd:pfam00047  84 TSL 86

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.

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                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 768006403 205 EVMEGSSMTFLAETKSHPPCAYTWF-----LLDS----ILSHTTRTFTIHAVSREHEGLYRCLVSNSATHLSS 268
Cdd:cd05760   12 EIQPSSRVTLRCHIDGHPRPTYQWFrdgtpLSDGqgnySVSSKERTLTLRSAGPDDSGLYYCCAHNAFGSVCS 84

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.

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                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 768006403 382 SASEMISTIEAELNSSLTLQCWAESKPGAEYRWTL---------EHSTGEHLGEQLIIRALTWEHDGIYNCTASNSLTGL 452
Cdd:cd20976    3 SFSSVPKDLEAVEGQDFVAQCSARGKPVPRITWIRnaqplqyaaDRSTCEAGVGELHIQDVLPEDHGTYTCLAKNAAGQV 82

                 ....*...
gi 768006403 453 ARSTSVLV 460
Cdd:cd20976   83 SCSAWVTV 90

agrin-responsive second immunoglobulin-like domains (Ig2) of the Muscle-specific kinase (MuSK) ectodomain; a member of the I-set of Ig superfamily domains; The members here are composed of the second immunoglobulin-like (Ig) domains of the Muscle-specific kinase (MuSK) ectodomain. MuSK is a receptor tyrosine kinase specifically expressed in skeletal muscle, where it plays a central role in the formation and maintenance of the neuromuscular junction (NMJ). MuSK is activated by agrin, a neuron-derived heparan sulfate proteoglycan. The activation of MUSK in myotubes regulates the formation of NMJs through the regulation of different processes including the specific expression of genes in subsynaptic nuclei, the reorganization of the actin cytoskeleton and the clustering of the acetylcholine receptors (AChR) in the postsynaptic membrane. 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 MuSK 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.

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                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 768006403 125 TIHWVSNNLSIVFHERMQLSKDGKiLTILIVQREDSGTYQCEARDALLSQRSDPIFLDVK 184
Cdd:cd20968   30 SVSWIKGDDLIKENNRIAVLESGS-LRIHNVQKEDAGQYRCVAKNSLGIAYSKPVTIEVE 88

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.

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                 ....*....|....*....|....*....|....*....|....*.
gi 768006403 125 TIHWVSNNLSIVFH-ERMQLSKDGKILTILIVQREDSGTYQCEARD 169
Cdd:cd04978   30 TITWRLNGVPIEPApEDMRRTVDGRTLIFSNLQPNDTAVYQCNASN 75