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
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 761631371  33 PSWEVMNGQQLTLEClvdisTTSKSRSQHRVLFYKDDAMVYNvtSREHTeSYVIPQARVFHSGKYKCTVMLNNKEKT 109
Cdd:cd05753    7 PSAVVFEGEPLTLRC-----HGWKDKKVHKVTYYKDGKALKF--SYENS-NFSIPQATLSDSGSYHCSGTVRIKRRS 75

Second immunoglobulin (Ig)-like domain of Fcgamma-receptors (FcgammaRs), and similar domains; The members here are composed of the second immunoglobulin (Ig)-like domain of Fcgamma-receptors (FcgammaRs). Interactions between IgG and FcgammaR are important to the initiation of cellular and humoral response. IgG binding to FcgammaR leads to a cascade of signals and ultimately to functions such as antibody-dependent-cellular-cytotoxicity (ADCC), endocytosis, phagocytosis, release of inflammatory mediators, etc. FcgammaR has two Ig-like domains. This group also contains FcepsilonRI which binds IgE with high affinity.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 761631371  33 PSWEVMNGQQLTLEClvdisTTSKSRSQHRVLFYKDDAMVYNvtSREHTeSYVIPQARVFHSGKYKCTVMLNNKEKT 109
Cdd:cd05753    7 PSAVVFEGEPLTLRC-----HGWKDKKVHKVTYYKDGKALKF--SYENS-NFSIPQATLSDSGSYHCSGTVRIKRRS 75

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 761631371 316 KPKLE--FSSSRLDQGELLDLSCSVSGTPVANFT-------------------IQKEETVLSqYQNFSKIAEEsDSGEYS 374
Cdd:cd20956    1 APVLLetFSEQTLQPGPSVSLKCVASGNPLPQITwtldgfpipesprfrvgdyVTSDGDVVS-YVNISSVRVE-DGGEYT 78

                         90
                 ....*....|.
gi 761631371 375 CTA--GIGKVV 383
Cdd:cd20956   79 CTAtnDVGSVS 89

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 761631371  495 SILSSNEVQSGSEMVLRCSVKEGTSPITFQFYKEK----EDRPFHQAVVNDTQAFWHNKQASKKQEGQYYCTASNRASS 569
Cdd:pfam00047   1 SAPPTVTVLEGDSATLTCSASTGSPGPDVTWSKEGgtliESLKVKHDNGRTTQSSLLISNVTKEDAGTYTCVVNNPGGS 79

Second immunoglobulin (Ig)-like domain of Fcgamma-receptors (FcgammaRs), and similar domains; The members here are composed of the second immunoglobulin (Ig)-like domain of Fcgamma-receptors (FcgammaRs). Interactions between IgG and FcgammaR are important to the initiation of cellular and humoral response. IgG binding to FcgammaR leads to a cascade of signals and ultimately to functions such as antibody-dependent-cellular-cytotoxicity (ADCC), endocytosis, phagocytosis, release of inflammatory mediators, etc. FcgammaR has two Ig-like domains. This group also contains FcepsilonRI which binds IgE with high affinity.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 761631371  33 PSWEVMNGQQLTLEClvdisTTSKSRSQHRVLFYKDDAMVYNvtSREHTeSYVIPQARVFHSGKYKCTVMLNNKEKT 109
Cdd:cd05753    7 PSAVVFEGEPLTLRC-----HGWKDKKVHKVTYYKDGKALKF--SYENS-NFSIPQATLSDSGSYHCSGTVRIKRRS 75

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 761631371  316 KPKL--EFSSSRLDQGELLDLSCSVSGTPVANFTIQKEETVL----SQYQNFSKI--------AEESDSGEYSCTA 377
Cdd:pfam13927   1 KPVItvSPSSVTVREGETVTLTCEATGSPPPTITWYKNGEPIssgsTRSRSLSGSnstltisnVTRSDAGTYTCVA 76

Second immunoglobulin (Ig)-like domain of Fcgamma-receptors (FcgammaRs), and similar domains; The members here are composed of the second immunoglobulin (Ig)-like domain of Fcgamma-receptors (FcgammaRs). Interactions between IgG and FcgammaR are important to the initiation of cellular and humoral response. IgG binding to FcgammaR leads to a cascade of signals and ultimately to functions such as antibody-dependent-cellular-cytotoxicity (ADCC), endocytosis, phagocytosis, release of inflammatory mediators, etc. FcgammaR has two Ig-like domains. This group also contains FcepsilonRI which binds IgE with high affinity.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 761631371 498 SSNEVQSGSEMVLRCSVKEGTSPITFQFYKEKEDRPFHQAVVNdtqafWHNKQASKKQEGQYYCTAsnrasSMRTSPRSS 577
Cdd:cd05753    7 PSAVVFEGEPLTLRCHGWKDKKVHKVTYYKDGKALKFSYENSN-----FSIPQATLSDSGSYHCSG-----TVRIKRRSS 76

                 ....*..
gi 761631371 578 -TLAVRV 583
Cdd:cd05753   77 eSVNITV 83

Immunoglobulin domain; This domain contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 761631371  505 GSEMVLRCSVKeGTSPITFQFYKEKEdrpfhqaVVNDTQAFwHNKQASKKQEGQYYCTASNRASSMRTSP 574
Cdd:pfam13895  14 GEPVTLTCSAP-GNPPPSYTWYKDGS-------AISSSPNF-FTLSVSAEDSGTYTCVARNGRGGKVSNP 74

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

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 761631371   329 GELLDLSCSVSGTPVANFTIQKEETVLSQYQNFSKI-------------AEESDSGEYSCTAGIGKVVKRSG 387
Cdd:smart00410   9 GESVTLSCEASGSPPPEVTWYKQGGKLLAESGRFSVsrsgststltisnVTPEDSGTYTCAATNSSGSASSG 80