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

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|
gi 281360540   441 GDTLKSRLRISNAQTTDTGNYTCQPTTAS---SASVLVHV 477
Cdd:smart00410  46 RSGSTSTLTISNVTPEDSGTYTCAATNSSgsaSSGTTLTV 85

Immunoglobulin variable domain (IgV); The members here are composed of the immunoglobulin variable domain (IgV). The IgV family contains the standard Ig superfamily V-set AGFCC'C"/DEB domain topology, and are components of immunoglobulin (Ig) and T cell receptors. The basic structure of Ig molecules is a tetramer of two light chains and two heavy chains linked by disulfide bonds. In Ig, each chain is composed of one variable domain (IgV) and one or more constant domains (IgC); these names reflect the fact that the variability in sequences is higher in the variable domain than in the constant domain. Within the variable domain, there are regions of even more variability called the hypervariable or complementarity-determining regions (CDRs) which are responsible for antigen binding. A predominant feature of most Ig domains is the disulfide bridge connecting 2 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" strands in the other.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 281360540 243 PRNITGRTGHTeAIIKCRVDSLHDKS-VSWIRKRD------LHILTVGTATYTSD--KRFQVTESKDSReWTLHVKAPLA 313
Cdd:cd00099    5 PRSLSVQEGES-VTLSCEVSSSFSSTyIYWYRQKPgqgpefLIYLSSSKGKTKGGvpGRFSGSRDGTSS-FSLTISNLQP 82

                         90
                 ....*....|
gi 281360540 314 KDSGIYECQV 323
Cdd:cd00099   83 EDSGTYYCAV 92

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

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|
gi 281360540   441 GDTLKSRLRISNAQTTDTGNYTCQPTTAS---SASVLVHV 477
Cdd:smart00410  46 RSGSTSTLTISNVTPEDSGTYTCAATNSSgsaSSGTTLTV 85

Immunoglobulin variable domain (IgV); The members here are composed of the immunoglobulin variable domain (IgV). The IgV family contains the standard Ig superfamily V-set AGFCC'C"/DEB domain topology, and are components of immunoglobulin (Ig) and T cell receptors. The basic structure of Ig molecules is a tetramer of two light chains and two heavy chains linked by disulfide bonds. In Ig, each chain is composed of one variable domain (IgV) and one or more constant domains (IgC); these names reflect the fact that the variability in sequences is higher in the variable domain than in the constant domain. Within the variable domain, there are regions of even more variability called the hypervariable or complementarity-determining regions (CDRs) which are responsible for antigen binding. A predominant feature of most Ig domains is the disulfide bridge connecting 2 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" strands in the other.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 281360540 243 PRNITGRTGHTeAIIKCRVDSLHDKS-VSWIRKRD------LHILTVGTATYTSD--KRFQVTESKDSReWTLHVKAPLA 313
Cdd:cd00099    5 PRSLSVQEGES-VTLSCEVSSSFSSTyIYWYRQKPgqgpefLIYLSSSKGKTKGGvpGRFSGSRDGTSS-FSLTISNLQP 82

                         90
                 ....*....|
gi 281360540 314 KDSGIYECQV 323
Cdd:cd00099   83 EDSGTYYCAV 92

Immunoglobulin (Ig) variable (V) domain of T-cell receptor (TCR) beta chain; The members here are composed of the immunoglobulin (Ig) variable domain of the beta chain of alpha/beta T-cell antigen receptors (TCRs). TCRs mediate antigen recognition by T lymphocytes, and are composed of alpha and beta, or gamma and delta, polypeptide chains with variable (V) and constant (C) regions. This group includes the variable domain of the alpha chain of alpha/beta TCRs. Alpha/beta TCRs recognize antigen as peptide fragments presented by major histocompatibility complex (MHC) molecules. The variable domain of TCRs is responsible for antigen recognition, and is located at the N-terminus of the receptor. Gamma/delta TCRs recognize intact protein antigens directly without antigen processing and recognize MHC independently of the bound peptide. Members of this group contain standard Ig superfamily V-set AGFCC'C"/DEB domain topology.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 281360540 243 PRNITGRTGhTEAIIKCRVDSLHDkSVSWIRKRD------LHILTVGTATYTSD---KRFQVTESKDSReWTLHVKAPLA 313
Cdd:cd05899    5 PRYLIKRRG-QSVTLRCSQKSGHD-NMYWYRQDPgkglqlLFYSYGGGLNEEGDlpgDRFSASRPSLTR-SSLTIKSAEP 81

                 ....*...
gi 281360540 314 KDSGIYEC 321
Cdd:cd05899   82 EDSAVYLC 89

First (N-terminal) immunoglobulin (Ig)-like domain of the nectin-like molecules; member of the V-set of Ig superfamily (IgSF) domains; The members here are composed of the N-terminal immunoglobulin (Ig)-like domain of the nectin-like molecules Necl-1 (also known as cell adhesion molecule 3 (CADM3)), Necl-2 (CADM1), Necl-3 (CADM2), and similar proteins. At least five nectin-like molecules have been identified (Necl-1 to Necl-5). They all have an extracellular region containing three Ig-like domains, a transmembrane region, and a cytoplasmic region. The N-terminal Ig-like domain of the extracellular region belongs to the V-type subfamily of Ig domains, is essential to cell-cell adhesion, and plays a part in the interaction with the envelope glycoprotein D of various viruses. Necl-1, Necl-2, and Necl-3 have Ca(2+)-independent homophilic and heterophilic cell-cell adhesion activity. Necl-1 is specifically expressed in neural tissue, and is important to the formation of synapses, axon bundles, and myelinated axons. Necl-2 is expressed in a wide variety of tissues and is a putative tumour suppressor gene which is downregulated in aggressive neuroblastoma. Necl-3 accumulates in central and peripheral nervous system tissue and has been shown to selectively interact with oligodendrocytes. This group also contains Class-I MHC-restricted T-cell-associated molecule (CRTAM), whose expression pattern is consistent with its expression in Class-I MHC-restricted T-cells.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 281360540 244 RNITGRTGHTeAIIKCRVDSLHDKSVSWIRKRDlHILTVGTATYTSDKRFQVTESKDSrEWTLHVKAPLAKDSGIYECQV 323
Cdd:cd05717    4 QDVTVVEGET-LTLKCQVSLRDDSSLQWLNPNG-QTIYFNDKRALRDSRYQLLNHSAS-ELSISVSNVTLSDEGVYTCLH 80

                 ....
gi 281360540 324 NTEP 327
Cdd:cd05717   81 YTDP 84