First immunoglobulin (Ig)-like domain of carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM); The members here are composed of the immunoglobulin (Ig)-like domain 1 in carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) proteins. 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 22758148 272 LRIDPVTPHAAEGESVLLQVHNLPEDLQTFSWYKGVDSTPSFQIVEYSKAMKSIISGSAYSRREIGYTNGSLLLQDVTEK 351
Cdd:cd05774   1 LTIELVPPQVAEGENVLLLVHNLPENLLAYAWYKGKTVSPNFLIASYIISTNSSTPGPAYSGRETIYPNGSLLIQNVTQK 80

                        90       100
                ....*....|....*....|....*
gi 22758148 352 DSGLYTLVTIDSNMRVETVHVQVNI 376
Cdd:cd05774  81 DTGFYTLQTITADLQTEQASVHLQV 105

First immunoglobulin (Ig)-like domain of carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM); The members here are composed of the immunoglobulin (Ig)-like domain 1 in carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) proteins. 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 22758148  36 VTIQS-PKHVVEGENILLQVDNLPENLLAFAWYRG-LINWRLTIALHFLDYSTSMTGPEHSDREILYSNGSLWIQNVTQE 113
Cdd:cd05774   1 LTIELvPPQVAEGENVLLLVHNLPENLLAYAWYKGkTVSPNFLIASYIISTNSSTPGPAYSGRETIYPNGSLLIQNVTQK 80

                        90       100
                ....*....|....*....|....*.
gi 22758148 114 DTGYYIFQTISNHGELEsNTSTFLQV 139
Cdd:cd05774  81 DTGFYTLQTITADLQTE-QASVHLQV 105

First immunoglobulin (Ig)-like domain of carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM); The members here are composed of the immunoglobulin (Ig)-like domain 1 in carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) proteins. 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 22758148 272 LRIDPVTPHAAEGESVLLQVHNLPEDLQTFSWYKGVDSTPSFQIVEYSKAMKSIISGSAYSRREIGYTNGSLLLQDVTEK 351
Cdd:cd05774   1 LTIELVPPQVAEGENVLLLVHNLPENLLAYAWYKGKTVSPNFLIASYIISTNSSTPGPAYSGRETIYPNGSLLIQNVTQK 80

                        90       100
                ....*....|....*....|....*
gi 22758148 352 DSGLYTLVTIDSNMRVETVHVQVNI 376
Cdd:cd05774  81 DTGFYTLQTITADLQTEQASVHLQV 105

First immunoglobulin (Ig)-like domain of carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM); The members here are composed of the immunoglobulin (Ig)-like domain 1 in carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) proteins. 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 22758148  36 VTIQS-PKHVVEGENILLQVDNLPENLLAFAWYRG-LINWRLTIALHFLDYSTSMTGPEHSDREILYSNGSLWIQNVTQE 113
Cdd:cd05774   1 LTIELvPPQVAEGENVLLLVHNLPENLLAYAWYKGkTVSPNFLIASYIISTNSSTPGPAYSGRETIYPNGSLLIQNVTQK 80

                        90       100
                ....*....|....*....|....*.
gi 22758148 114 DTGYYIFQTISNHGELEsNTSTFLQV 139
Cdd:cd05774  81 DTGFYTLQTITADLQTE-QASVHLQV 105

Immunoglobulin V-set domain; This domain is found in antibodies as well as neural protein P0 and CTL4 amongst others.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 22758148   274 IDPVTPHAAEGESVLLQVHNLP---EDLQTFSWYKG-VDSTPSFQIVEYSKAMKSIISGSAYS-RREIGYTNGSLLLQDV 348
Cdd:pfam07686   1 QTPREVTVALGGSVTLPCTYSSsmsEASTSVYWYRQpPGKGPTFLIAYYSNGSEEGVKKGRFSgRGDPSNGDGSLTIQNL 80

                          90       100
                  ....*....|....*....|....*....
gi 22758148   349 TEKDSGLYTLVTIDSNMRVETVHVQVNIY 377
Cdd:pfam07686  81 TLSDSGTYTCAVIPSGEGVFGKGTRLTVL 109

Immunoglobulin V-set domain; This domain is found in antibodies as well as neural protein P0 and CTL4 amongst others.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 22758148   157 IESVPPRVAEGGRVLLRVHNLPEY---LQLFFWYKG-VIMIHKVEIVRHRTLKNLSDPGPAHSGRE-IVFSNGSLLLQNV 231
Cdd:pfam07686   1 QTPREVTVALGGSVTLPCTYSSSMseaSTSVYWYRQpPGKGPTFLIAYYSNGSEEGVKKGRFSGRGdPSNGDGSLTIQNL 80

                          90       100
                  ....*....|....*....|....*...
gi 22758148   232 TWKDTGFYTLQTVNGFREMELAHIYLQV 259
Cdd:pfam07686  81 TLSDSGTYTCAVIPSGEGVFGKGTRLTV 108

Immunoglobulin V-set domain; This domain is found in antibodies as well as neural protein P0 and CTL4 amongst others.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 22758148    39 QSPK--HVVEGENILLQV---DNLPENLLAFAWYRGLINWRLTIALHFldYSTSMTGPEHSDR-----EILYSNGSLWIQ 108
Cdd:pfam07686   1 QTPRevTVALGGSVTLPCtysSSMSEASTSVYWYRQPPGKGPTFLIAY--YSNGSEEGVKKGRfsgrgDPSNGDGSLTIQ 78

                          90       100       110
                  ....*....|....*....|....*....|..
gi 22758148   109 NVTQEDTGYYIFQTISNhGELESNTSTFLQVY 140
Cdd:pfam07686  79 NLTLSDSGTYTCAVIPS-GEGVFGKGTRLTVL 109

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

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 22758148     39 QSPKHVVEGENILLQ--VDNLPENllAFAWYRGLINWrltialhfLDYSTSMTGPEHSdreilySNGSLWIQNVTQEDTG 116
Cdd:smart00410   1 PPSVTVKEGESVTLSceASGSPPP--EVTWYKQGGKL--------LAESGRFSVSRSG------STSTLTISNVTPEDSG 64

                           90       100
                   ....*....|....*....|...
gi 22758148    117 YYIFQTISNHGELESNTStfLQV 139
Cdd:smart00410  65 TYTCAATNSSGSASSGTT--LTV 85

First immunoglobulin (Ig)-like domain of carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM); The members here are composed of the immunoglobulin (Ig)-like domain 1 in carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) proteins. 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 22758148 272 LRIDPVTPHAAEGESVLLQVHNLPEDLQTFSWYKGVDSTPSFQIVEYSKAMKSIISGSAYSRREIGYTNGSLLLQDVTEK 351
Cdd:cd05774   1 LTIELVPPQVAEGENVLLLVHNLPENLLAYAWYKGKTVSPNFLIASYIISTNSSTPGPAYSGRETIYPNGSLLIQNVTQK 80

                        90       100
                ....*....|....*....|....*
gi 22758148 352 DSGLYTLVTIDSNMRVETVHVQVNI 376
Cdd:cd05774  81 DTGFYTLQTITADLQTEQASVHLQV 105

First immunoglobulin (Ig)-like domain of carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM); The members here are composed of the immunoglobulin (Ig)-like domain 1 in carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) proteins. 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 22758148  36 VTIQS-PKHVVEGENILLQVDNLPENLLAFAWYRG-LINWRLTIALHFLDYSTSMTGPEHSDREILYSNGSLWIQNVTQE 113
Cdd:cd05774   1 LTIELvPPQVAEGENVLLLVHNLPENLLAYAWYKGkTVSPNFLIASYIISTNSSTPGPAYSGRETIYPNGSLLIQNVTQK 80

                        90       100
                ....*....|....*....|....*.
gi 22758148 114 DTGYYIFQTISNHGELEsNTSTFLQV 139
Cdd:cd05774  81 DTGFYTLQTITADLQTE-QASVHLQV 105

Immunoglobulin (Ig)-like domain of carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) and similar proteins; The members here are composed of the immunoglobulin (Ig)-like domain in carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) and related 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. 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. This family corresponds to the D1 Ig-like domain. Also belonging to this group is the N-terminal immunoglobulin (Ig)-like domain of the signaling lymphocyte activation molecule (SLAM) family, CD84-like family. The SLAM family is a group of immune-cell specific receptors that can regulate both adaptive and innate immune responses. SLAM family proteins are organized as an extracellular domain with having two or four Ig-like domains, a single transmembrane segment, and a cytoplasmic region having Tyr-based motifs. The extracellular domain is organized as a membrane-distal Ig variable (IgV) domain that is responsible for ligand recognition and a membrane-proximal truncated Ig constant-2 (IgC2) domain.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 22758148 279 PHAAEGESVLLQVHNLPEDLQTFSWYKGVDSTPSFQIVEYSKAMKSIISGSAYSRREIGYTNGSLLLQDVTEKDSGLYTL 358
Cdd:cd05741   5 FYGAEGKNVLLLVPNLQTPLKSVSWYKGKQVSRNDEIAEYENSSDEFRAGSAFSGREYIYTNGSLLIQNITLSDTGFYTL 84

                        90
                ....*....|....*...
gi 22758148 359 VTIDSNMRVETVHVQVNI 376
Cdd:cd05741  85 ESTNIGGKTESATFQLHV 102

Immunoglobulin (Ig)-like domain of carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) and similar proteins; The members here are composed of the immunoglobulin (Ig)-like domain in carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) and related 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. 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. This family corresponds to the D1 Ig-like domain. Also belonging to this group is the N-terminal immunoglobulin (Ig)-like domain of the signaling lymphocyte activation molecule (SLAM) family, CD84-like family. The SLAM family is a group of immune-cell specific receptors that can regulate both adaptive and innate immune responses. SLAM family proteins are organized as an extracellular domain with having two or four Ig-like domains, a single transmembrane segment, and a cytoplasmic region having Tyr-based motifs. The extracellular domain is organized as a membrane-distal Ig variable (IgV) domain that is responsible for ligand recognition and a membrane-proximal truncated Ig constant-2 (IgC2) domain.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 22758148  37 TIQSPkHVVEGENILLQVDNLPENLLAFAWYRG-LINWRLTIALHFLDYSTSMTGPEHSDREILYSNGSLWIQNVTQEDT 115
Cdd:cd05741   1 SSEQF-YGAEGKNVLLLVPNLQTPLKSVSWYKGkQVSRNDEIAEYENSSDEFRAGSAFSGREYIYTNGSLLIQNITLSDT 79

                        90       100
                ....*....|....*....|....
gi 22758148 116 GYYIFQTISNHGELEsNTSTFLQV 139
Cdd:cd05741  80 GFYTLESTNIGGKTE-SATFQLHV 102

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 22758148 398 VVFTC-FSDNTGVSIRWLFNNQSLQLT--ERMTLSPSKCQLRIHTVRKEDAGEYQCEAFNPVSSKTS 461
Cdd:cd00096   1 VTLTCsASGNPPPTITWYKNGKPLPPSsrDSRRSELGNGTLTISNVTLEDSGTYTCVASNSAGGSAS 67

N-terminal immunoglobulin (Ig)-like domain of T-cell surface antigen CD2, and similar domains; The members here are composed of the N-terminal immunoglobulin (Ig)-like domain (or domain 1) of T-cell surface antigen Clusters of Differentiation (CD) 2 and similar proteins. CD2 is a T-cell specific surface glycoprotein and is critically important for mediating adhesion between T cells and antigen-presenting cells or between cytolytic T cells and target cells. CD2 is located on chromosome 1 at 1p13 in humans and on chromosome 3 in mice. CD2 contains an extracellular domain with two or Ig-like domains, a single transmembrane segment, and a cytoplasmic region rich in proline and basic residues.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 22758148 281 AAEGESVLLQVHNLPEDLQTFSWYKGvdstpSFQIVEYSKAMKSIISGSAYSRREIGYTNGSLLLQDVTEKDSGLYTLVT 360
Cdd:cd05775   7 GALGGNVTLTISSLQDDIDEIKWKKT-----KDKIVEWENNIGPTYFGSFKDRVLLDKESGSLTIKNLTKEDSGTYELEI 81

                ....*...
gi 22758148 361 IDSNMRVE 368
Cdd:cd05775  82 TSTNGKVL 89

Immunoglobulin I-set domain;

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 22758148   389 DSTVRVQSSVVFTCfsDNTGV---SIRWLFNNQSLQLTER--MTLSPSKCQLRIHTVRKEDAGEYQCEAFNPVSSKTS 461
Cdd:pfam07679   9 DVEVQEGESARFTC--TVTGTpdpEVSWFKDGQPLRSSDRfkVTYEGGTYTLTISNVQPDDSGKYTCVATNSAGEAEA 84

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.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 22758148 380 VTQPAMRVTdstVRVQSSVVFTCFS-DNTGVSIRWLFNNQSLQLTERMTLSPSKcQLRIHTVRKEDAGEYQCEAFNPVSS 458
Cdd:cd20968   2 ITRPPTNVT---IIEGLKAVLPCTTmGNPKPSVSWIKGDDLIKENNRIAVLESG-SLRIHNVQKEDAGQYRCVAKNSLGI 77

                        90
                ....*....|
gi 22758148 459 KTSLPVSLAV 468
Cdd:cd20968  78 AYSKPVTIEV 87

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 22758148   391 TVRVQSSVVFTCFS--DNTGVSIRWLFNNQslQLTERMTLSPSKCQLRIHT-----VRKEDAGEYQCEAFNPVSSKTS 461
Cdd:pfam00047   7 TVLEGDSATLTCSAstGSPGPDVTWSKEGG--TLIESLKVKHDNGRTTQSSllisnVTKEDAGTYTCVVNNPGGSATL 82

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 22758148 378 KLVTQPamrvTDSTVRVQSSVVFTCFSD-NTGVSIRW--------LFNNQSLQLTERMTLSPSKcQLRIHTVRKEDAGEY 448
Cdd:cd05726   1 QFVVKP----RDQVVALGRTVTFQCETKgNPQPAIFWqkegsqnlLFPYQPPQPSSRFSVSPTG-DLTITNVQRSDVGYY 75

                        90
                ....*....|
gi 22758148 449 QCEAFNPVSS 458
Cdd:cd05726  76 ICQALNVAGS 85

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 22758148 389 DSTVRVQSSVVFTC-FSDNTGVSIRWLFNNQSLQLTERMTLSpSKCQLRIHTVRKEDAGEYQCEAFNPVSS 458
Cdd:cd20957  10 VQTVDFGRTAVFNCsVTGNPIHTVLWMKDGKPLGHSSRVQIL-SEDVLVIPSVKREDKGMYQCFVRNDGDS 79

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
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 22758148 387 VTDSTVRVQSSVVFTC-FSDNTGVSIRWLFNNQSLQLTERMTLSPSKcqLRIHTVRKEDAGEYQCEAFN 454
Cdd:cd05728   6 ISDTEADIGSSLRWECkASGNPRPAYRWLKNGQPLASENRIEVEAGD--LRITKLSLSDSGMYQCVAEN 72

IL-1 receptor-like protein; Provisional

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 22758148  302 SWYKgvdsTPSFQIVEYSKAMKSIisgSAYSRREIGYTNGSLLLQDVTEKDSGLYtLVTIDSNMRVETVHVQVNI-YKLV 380
Cdd:PHA02826  66 TWSK----TDSLAFVRDSGARTKI---KKITHNEIGDRSENLWIGNVINIDEGIY-ICTISSGNICEESTIRLTFdSGTI 137

                         90       100       110       120       130       140       150
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 22758148  381 TQPAMRVTDSTVRVQSSVVF-TCFSDNTgvsIRWLFNNQSLQLTERMTLSPSKCQLRIHTVRKEDAGEYQC 450
Cdd:PHA02826 138 NYQFNSGKDSKLHCYGTDGIsSTFKDYT---LTWYKNGNIVLYTDRIQLRNNNSTLVIKSATHDDSGIYTC 205

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
                ....*....|....*....|....*....|....*...
gi 22758148  98 ILYSNGSLWIQNVTQEDTGYYIFQTISNHGELESNTST 135
Cdd:cd20978  49 ATVEDGTLTIINVQPEDTGYYGCVATNEIGDIYTETLL 86

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 22758148 410 SIRWLFNNQSLQLTERMTLSPSKcQLRIHTV-RKEDAGEYQCEAFNP 455
Cdd:cd20958  31 SITWEKDGRRLPLNHRQRVFPNG-TLVIENVqRSSDEGEYTCTARNQ 76

N-terminal immunoglobulin (Ig)-like domain of T-cell surface antigen CD2, and similar domains; The members here are composed of the N-terminal immunoglobulin (Ig)-like domain (or domain 1) of T-cell surface antigen Clusters of Differentiation (CD) 2 and similar proteins. CD2 is a T-cell specific surface glycoprotein and is critically important for mediating adhesion between T cells and antigen-presenting cells or between cytolytic T cells and target cells. CD2 is located on chromosome 1 at 1p13 in humans and on chromosome 3 in mice. CD2 contains an extracellular domain with two or Ig-like domains, a single transmembrane segment, and a cytoplasmic region rich in proline and basic residues.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 22758148  45 VEGENILLQVDNLPENLLAFAWYRG---LINWRLTIALhflDYSTSMtgpehSDR-EILYSNGSLWIQNVTQEDTGYYIF 120
Cdd:cd05775   8 ALGGNVTLTISSLQDDIDEIKWKKTkdkIVEWENNIGP---TYFGSF-----KDRvLLDKESGSLTIKNLTKEDSGTYEL 79

                        90       100
                ....*....|....*....|.
gi 22758148 121 QTISNHGELESntSTF-LQVY 140
Cdd:cd05775  80 EITSTNGKVLS--SKFtLEVL 98

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 22758148    35 SVTIQSPKHVV-EGENILL--QVDNLPENllAFAWYRGlinwrltialhfldySTSMTGPEHSDREILYSNGSLWIQNVT 111
Cdd:pfam13927   3 VITVSPSSVTVrEGETVTLtcEATGSPPP--TITWYKN---------------GEPISSGSTRSRSLSGSNSTLTISNVT 65

                  ....*..
gi 22758148   112 QEDTGYY 118
Cdd:pfam13927  66 RSDAGTY 72