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 12655652   5 IVMTQTPLSSPVTLGQPASISCRSSQSLvhsdGNTYLSWLQQRPGQPPRLLIYKISNRFSGVPDRFSGSGAGTDFTLKIS 84
Cdd:cd04980   1 IVMTQSPASLSVSPGERVTISCKASQSI----SSNYLAWYQQKPGQAPKLLIYYASTLHSGVPSRFSGSGSGTDFTLTIS 76

                        90       100
                ....*....|....*....|.
gi 12655652  85 RVEAEDVGVYYCMQATQFPQT 105
Cdd:cd04980  77 SVEPEDAAVYYCQQGYTFPYT 97

Immunoglobulin (Ig) light chain, kappa type, variable (V) domain; The members here are composed of the immunoglobulin (Ig) light chain, kappa type, variable (V) domain. This group contains the standard Ig superfamily V-set AGFCC'C"/DEB domain topology. The basic structure of Ig molecules is a tetramer of two light chains and two heavy chains linked by disulfide bonds. There are two types of light chains: kappa and lambda, each composed of a constant domain (CL) and a variable domain (VL). There are five types of heavy chains (alpha, gamma, delta, epsilon, and mu), which determines the type of immunoglobulin formed: IgA, IgG, IgD, IgE, and IgM, respectively. In higher vertebrates, there are two types of light chain, designated kappa and lambda, which seem to be functionally identical, and can associate with any of the heavy chains.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 12655652   5 IVMTQTPLSSPVTLGQPASISCRSSQSLvhsdGNTYLSWLQQRPGQPPRLLIYKISNRFSGVPDRFSGSGAGTDFTLKIS 84
Cdd:cd04980   1 IVMTQSPASLSVSPGERVTISCKASQSI----SSNYLAWYQQKPGQAPKLLIYYASTLHSGVPSRFSGSGSGTDFTLTIS 76

                        90       100
                ....*....|....*....|.
gi 12655652  85 RVEAEDVGVYYCMQATQFPQT 105
Cdd:cd04980  77 SVEPEDAAVYYCQQGYTFPYT 97

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 12655652     9 QTPLSSPVTLGQPASISCrsSQSLVHSDGNTYLSWLQQRPGQPPRLLI--YKISNRFSGVPDRFSGSG--AGTDFTLKIS 84
Cdd:pfam07686   1 QTPREVTVALGGSVTLPC--TYSSSMSEASTSVYWYRQPPGKGPTFLIayYSNGSEEGVKKGRFSGRGdpSNGDGSLTIQ 78

                          90
                  ....*....|...
gi 12655652    85 RVEAEDVGVYYCM 97
Cdd:pfam07686  79 NLTLSDSGTYTCA 91

Immunoglobulin (Ig) light chain, kappa type, variable (V) domain; The members here are composed of the immunoglobulin (Ig) light chain, kappa type, variable (V) domain. This group contains the standard Ig superfamily V-set AGFCC'C"/DEB domain topology. The basic structure of Ig molecules is a tetramer of two light chains and two heavy chains linked by disulfide bonds. There are two types of light chains: kappa and lambda, each composed of a constant domain (CL) and a variable domain (VL). There are five types of heavy chains (alpha, gamma, delta, epsilon, and mu), which determines the type of immunoglobulin formed: IgA, IgG, IgD, IgE, and IgM, respectively. In higher vertebrates, there are two types of light chain, designated kappa and lambda, which seem to be functionally identical, and can associate with any of the heavy chains.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 12655652   5 IVMTQTPLSSPVTLGQPASISCRSSQSLvhsdGNTYLSWLQQRPGQPPRLLIYKISNRFSGVPDRFSGSGAGTDFTLKIS 84
Cdd:cd04980   1 IVMTQSPASLSVSPGERVTISCKASQSI----SSNYLAWYQQKPGQAPKLLIYYASTLHSGVPSRFSGSGSGTDFTLTIS 76

                        90       100
                ....*....|....*....|.
gi 12655652  85 RVEAEDVGVYYCMQATQFPQT 105
Cdd:cd04980  77 SVEPEDAAVYYCQQGYTFPYT 97

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 12655652   7 MTQTPLSSPVTLGQPASISCRSSQSlvhsDGNTYLSWLQQRPGQPPRLLIYKISNRFS---GVPDRFSGSG-AGTDFTLK 82
Cdd:cd00099   1 VTQSPRSLSVQEGESVTLSCEVSSS----FSSTYIYWYRQKPGQGPEFLIYLSSSKGKtkgGVPGRFSGSRdGTSSFSLT 76

                        90
                ....*....|....*.
gi 12655652  83 ISRVEAEDVGVYYCMQ 98
Cdd:cd00099  77 ISNLQPEDSGTYYCAV 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 12655652   8 TQTPLSSPVTLGQPASISCRssqslvHSDGNTYLSWLQQRPGQPPRLLIY---KISNRFSGVP-DRFSGSGA-GTDFTLK 82
Cdd:cd05899   2 TQSPRYLIKRRGQSVTLRCS------QKSGHDNMYWYRQDPGKGLQLLFYsygGGLNEEGDLPgDRFSASRPsLTRSSLT 75

                        90
                ....*....|....
gi 12655652  83 ISRVEAEDVGVYYC 96
Cdd:cd05899  76 IKSAEPEDSAVYLC 89

Immunoglobulin (Ig) variable (V) domain of T-cell receptor (TCR) gamma chain; The members here are composed of the immunoglobulin (Ig) variable (V) domain of the gamma chain of gamma/delta T-cell receptors (TCRs). TCRs mediate antigen recognition by T lymphocytes, and are heterodimers consisting of alpha and beta chains or gamma and delta chains. Each chain contains a variable (V) and a constant (C) region. The majority of T cells contain alpha/beta TCRs, but a small subset contain gamma/delta TCRs. Alpha/beta TCRs recognize antigens as peptide fragments presented by major histocompatibility complex (MHC) molecules. Gamma/delta TCRs recognize intact protein antigens directly without antigen processing and recognize MHC independently of the bound peptide. Gamma/delta T cells can also be stimulated by non-peptide antigens such as small phosphate- or amine-containing compounds. The variable domain of gamma/delta TCRs is responsible for antigen recognition and is located at the N-terminus of the receptor. Members of this group contain the standard Ig superfamily V-set AGFCC'C"/DEB domain topology.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 12655652   7 MTQTPLSSPVTLGQPASISCRSSQSLVHsdgNTYLSWLQQRPGQPPRLLIYKISN----RFSG-VPDRFSGS--GAGTDF 79
Cdd:cd04982   1 LEQPQLSITREESKSVTISCKVSGIDFS---TTYIHWYRQKPGQALERLLYVSSTsavrKDSGkTKNKFEARkdVGKSTS 77

                        90
                ....*....|....*..
gi 12655652  80 TLKISRVEAEDVGVYYC 96
Cdd:cd04982  78 TLTITNLEKEDSATYYC 94

Immunoglobulin (Ig) variable (V) domain of T-cell receptor (TCR) alpha chain and similar proteins; The members here are composed of the immunoglobulin (Ig) variable domain of the alpha 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 represents the variable domain of the alpha chain of TCRs and also includes the variable domain of delta chains of 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 12655652   8 TQTPLSSPVTLGQPASISCRSSQSlvhsdGNTYLSWLQQRPGQPPRLLIY-------KISNRFSGVPDRFSGSgagtdFT 80
Cdd:cd04983   2 TQSPQSLSVQEGENVTLNCNYSTS-----TFYYLFWYRQYPGQGPQFLIYissdsgnKKKGRFSATLDKSRKS-----SS 71

                        90
                ....*....|....*.
gi 12655652  81 LKISRVEAEDVGVYYC 96
Cdd:cd04983  72 LHISAAQLSDSAVYFC 87

Immunoglobulin (Ig) variable (V) domain of T-cell receptor (TCR) delta chain; The members here are composed of the immunoglobulin (Ig) variable (V) domain of the delta chain of gamma/delta T-cell receptors (TCRs). TCRs mediate antigen recognition by T lymphocytes, and are heterodimers consisting of alpha and beta chains or gamma and delta chains. Each chain contains a variable (V) and a constant (C) region. The majority of T cells contain alpha/beta TCRs, but a small subset contain gamma/delta TCRs. Alpha/beta TCRs recognize antigen as peptide fragments presented by major histocompatibility complex (MHC) molecules. Gamma/delta TCRs recognize intact protein antigens; they recognize protein antigens directly and without antigen processing, and MHC independently of the bound peptide. Gamma/delta T cells can also be stimulated by non-peptide antigens such as small phosphate- or amine-containing compounds. The variable domain of gamma/delta TCRs is responsible for antigen recognition and is located at the N-terminus of the receptor. Members of this group contain standard Ig superfamily V-set AGFCC'C"/DEB domain topology.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 12655652   9 QTPLSSPVtlGQPASISCRSSQSlvhsDGNTYLSWLQQRPGQPPRLLIYKISNRFSGVPDRFSGS--GAGTDFTLKISRV 86
Cdd:cd07706   6 QPDVSVQV--GEEVTLNCRYETS----WTNYYLFWYKQLPSGEMTFLIRQDSSEQNAKSGRYSVNfqKAQKSISLTISAL 79

                        90
                ....*....|
gi 12655652  87 EAEDVGVYYC 96
Cdd:cd07706  80 QLEDSAKYFC 89

Immunoglobulin variable domain (IgV) Cluster of Differentiation (CD) 79B; The members here are composed of the immunoglobulin variable domain (IgV) of the Cluster of Differentiation (CD) 79B (also known as CD79b molecule, immunoglobulin-associated beta (Ig-beta), and B29). The B lymphocyte antigen receptor is a multimeric complex that includes the antigen-specific component, surface immunoglobulin (Ig). Surface Ig non-covalently associates with two other proteins, Ig-alpha and Ig-beta, which are necessary for expression and function of the B-cell antigen receptor. This gene encodes the Ig-beta protein of the B-cell antigen component. Alternatively spliced transcript variants encoding different isoforms have been described. Members of the IgV family 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. Members of this group contain standard Ig superfamily V-set AGFCC'C"/DEB domain topology.

                        10        20        30        40        50        60
                ....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 12655652  34 HSDGNTYLSWLQQRPGQPPRLLIYKisnrfsgvPDRFSGSGAGTDFTLKISRVEAEDVGVYYCMQ 98
Cdd:cd16096  21 YTNYSGVMTWFRKKGNQRPQELFPE--------DGRISQTQNGSVYTLTIQNIQYEDNGIYFCQQ 77

First immunoglobulin variable (IgV) domain of poliovirus receptor (PVR, also known as CD155 and necl-5), and similar domains; The members here are composed of the first immunoglobulin (Ig) domain of poliovirus receptor (PVR, also known as CD155 and nectin-like protein 5 (necl-5)). Poliovirus (PV) binds to its cellular receptor (PVR/CD155) to initiate infection. CD155 is a membrane-anchored, single-span glycoprotein; its extracellular region has three Ig-like domains. There are four different isotypes of CD155 (referred to as alpha, beta, gamma, and delta), that result from alternate splicing of the CD155 mRNA, and have identical extracellular domains. CD155-beta and CD155-gamma are secreted; CD155-alpha and CD155-delta are membrane-bound and function as PV receptors. The virus recognition site is contained in the amino-terminal domain, D1. Having the virus attachment site on the receptor distal from the plasma membrane may be important for successful initiation of infection of cells by the virus. CD155 binds in the poliovirus "canyon" with a footprint similar to that of the intercellular adhesion molecule-1 receptor on human rhinoviruses. This group also includes the first Ig-like domain of nectin-1 (also known as poliovirus receptor related protein(PVRL)1; CD111), nectin-3 (also known as PVRL 3), nectin-4 (also known as PVRL4; LNIR receptor)and DNAX accessory molecule 1 (DNAM-1; CD226).

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 12655652   9 QTPLSSPVTLGQPASISCrssqsLVHSDGNTYLS---WLQQRPGQPPRLLIY----------KISNRFSGVPDRFSGSGA 75
Cdd:cd05718   4 QVPTEVTGFLGGSVTLPC-----SLTSPGTTKITqvtWMKIGAGSSQNVAVFhpqygpsvpnPYAERVEFLAARLGLRNA 78

                        90       100
                ....*....|....*....|....*....
gi 12655652  76 gtdfTLKISRVEAEDVGVYYCMQATqFPQ 104
Cdd:cd05718  79 ----TLRIRNLRVEDEGNYICEFAT-FPQ 102

Immunoglobulin (Ig) heavy chain (H), variable (V) domain; The members here are composed of the immunoglobulin (Ig) heavy chain (H), variable (V) domain. This group contains the standard Ig superfamily V-set AGFCC'C"/DEB domain topology. 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. There are five types of heavy chains (alpha, gamma, delta, epsilon, and mu), which determines the type of immunoglobulin formed: IgA, IgG, IgD, IgE, and IgM, respectively. In higher vertebrates, there are two types of light chain, designated kappa and lambda, which can associate with any of the heavy chains. This family includes alpha, gamma, delta, epsilon, and mu heavy chains.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 12655652  19 GQPASISCRSSQSlvhSDGNTYLSWLQQRPGQPPRLL--IY----------KISNRFSgvpdrFSGSGAGTDFTLKISRV 86
Cdd:cd04981  13 GQSLKLSCKASGF---TFTSYGMGWVRQAPGKGLEWIglIYpgggdtyyadSFKGRFT-----ITRDTSKSTAYLQLNSL 84

                        90
                ....*....|
gi 12655652  87 EAEDVGVYYC 96
Cdd:cd04981  85 TSEDTAVYYC 94