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 1098883676  24 IQMTQSPSSLSASVGDRVTITCQASQDI-SNYLNWYQQKPGKAPKLLIYDASNLETGVPSRFSGSGSGTDFTFTISSLQP 102
Cdd:cd04980     1 IVMTQSPASLSVSPGERVTISCKASQSIsSNYLAWYQQKPGQAPKLLIYYASTLHSGVPSRFSGSGSGTDFTLTISSVEP 80

                          90
                  ....*....|....*
gi 1098883676 103 EDIATYYCQQYDNLP 117
Cdd:cd04980    81 EDAAVYYCQQGYTFP 95

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 1098883676  24 IQMTQSPSSLSASVGDRVTITCQASQDI-SNYLNWYQQKPGKAPKLLIYDASNLETGVPSRFSGSGSGTDFTFTISSLQP 102
Cdd:cd04980     1 IVMTQSPASLSVSPGERVTISCKASQSIsSNYLAWYQQKPGQAPKLLIYYASTLHSGVPSRFSGSGSGTDFTLTISSVEP 80

                          90
                  ....*....|....*
gi 1098883676 103 EDIATYYCQQYDNLP 117
Cdd:cd04980    81 EDAAVYYCQQGYTFP 95

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 1098883676  28 QSPSSLSASVGDRVTITCQASQDISN---YLNWYQQKPGKAPKLLIYDASNL--ETGVPSRFSGSG--SGTDFTFTISSL 100
Cdd:pfam07686   1 QTPREVTVALGGSVTLPCTYSSSMSEastSVYWYRQPPGKGPTFLIAYYSNGseEGVKKGRFSGRGdpSNGDGSLTIQNL 80

                          90
                  ....*....|.
gi 1098883676 101 QPEDIATYYCQ 111
Cdd:pfam07686  81 TLSDSGTYTCA 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 1098883676  24 IQMTQSPSSLSASVGDRVTITCQASQDI-SNYLNWYQQKPGKAPKLLIYDASNLETGVPSRFSGSGSGTDFTFTISSLQP 102
Cdd:cd04980     1 IVMTQSPASLSVSPGERVTISCKASQSIsSNYLAWYQQKPGQAPKLLIYYASTLHSGVPSRFSGSGSGTDFTLTISSVEP 80

                          90
                  ....*....|....*
gi 1098883676 103 EDIATYYCQQYDNLP 117
Cdd:cd04980    81 EDAAVYYCQQGYTFP 95

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 1098883676  26 MTQSPSSLSASVGDRVTITCQASQ-DISNYLNWYQQKPGKAPKLLIYDASNLET---GVPSRFSGSGSG-TDFTFTISSL 100
Cdd:cd00099     1 VTQSPRSLSVQEGESVTLSCEVSSsFSSTYIYWYRQKPGQGPEFLIYLSSSKGKtkgGVPGRFSGSRDGtSSFSLTISNL 80

                          90
                  ....*....|....*
gi 1098883676 101 QPEDIATYYCQQYDN 115
Cdd:cd00099    81 QPEDSGTYYCAVSES 95

Immunoglobulin V-Type;

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1098883676   41 VTITCQASQD--ISNYLNWYQQKPGKAPKLLIYDASN----LETGVPSRFSGSG--SGTDFTFTISSLQPEDIATYYCQQ 112
Cdd:smart00406   2 VTLSCKFSGStfSSYYVSWVRQPPGKGLEWLGYIGSNgssyYQESYKGRFTISKdtSKNDVSLTISNLRVEDTGTYYCAV 81

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 1098883676  27 TQSPSSLSASVGDRVTITCqaSQDIS-NYLNWYQQKPGKAPKLLIYDASNL---ETGVP-SRFSGSG-SGTDFTFTISSL 100
Cdd:cd05899     2 TQSPRYLIKRRGQSVTLRC--SQKSGhDNMYWYRQDPGKGLQLLFYSYGGGlneEGDLPgDRFSASRpSLTRSSLTIKSA 79

                          90
                  ....*....|
gi 1098883676 101 QPEDIATYYC 110
Cdd:cd05899    80 EPEDSAVYLC 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 1098883676  26 MTQSPSSLSASVGDRVTITCQAS-QDISN-YLNWYQQKPGKAPKLLIYDASnleTGVPSRFSGSGSG----------TDF 93
Cdd:cd04982     1 LEQPQLSITREESKSVTISCKVSgIDFSTtYIHWYRQKPGQALERLLYVSS---TSAVRKDSGKTKNkfearkdvgkSTS 77

                          90
                  ....*....|....*..
gi 1098883676  94 TFTISSLQPEDIATYYC 110
Cdd:cd04982    78 TLTITNLEKEDSATYYC 94

Immunoglobulin (Ig)-like variable (V) domain of Cluster of Differentiation (CD) 8 alpha chain; The members here are composed of the immunoglobulin (Ig)-like variable domain of the Cluster of Differentiation (CD) 8 alpha. The CD8 glycoprotein plays an essential role in the control of T-cell selection, maturation, and the T-cell receptor (TCR)-mediated response to peptide antigen. CD8 is comprised of alpha and beta subunits and is expressed as either an alpha/alpha or alpha/beta dimer. Both dimeric isoforms can serve as a coreceptor for T cell activation and differentiation, however they have distinct physiological roles, different cellular distributions, unique binding partners, etc. Each CD8 subunit is comprised of an extracellular domain containing a V-type Ig-like domain, a single pass transmembrane portion, and a short intracellular domain. The Ig domain of CD8 alpha binds to antibodies. Members of this group contain standard Ig superfamily V-set AGFCC'C"/DEB domain topology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1098883676  29 SPSSLSASVGDRVTITCQASQDISNYLNWYQQKPGKAPKL--LIYDASNLETGVP-----SRFSGSGSGTDFTFTISSLQ 101
Cdd:cd05720     4 SPRKRDAQLGQKVELVCEVLNSVPQGCSWLFQPRGSAPQPtfLLYLSSSNKTKWAegldsKRFSGSRSGSSYVLTLKDFR 83

                  ....*....
gi 1098883676 102 PEDIATYYC 110
Cdd:cd05720    84 KEDEGYYFC 92

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1098883676  25 QMTQSPSSLSASVGDRVTITCQASQDISNYLNWYqqKPGKApklliydasNLETGVPSRFSGSGSGtdfTFTISSLQPED 104
Cdd:pfam13927   3 VITVSPSSVTVREGETVTLTCEATGSPPPTITWY--KNGEP---------ISSGSTRSRSLSGSNS---TLTISNVTRSD 68

                  ....*..
gi 1098883676 105 IATYYCQ 111
Cdd:pfam13927  69 AGTYTCV 75

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 1098883676  38 GDRVTITCQASQDI--SNYLNWYQQKPGKAPKLL--IYDA---SNLETGVPSRFSGS--GSGTDFTFTISSLQPEDIATY 108
Cdd:cd04981    13 GQSLKLSCKASGFTftSYGMGWVRQAPGKGLEWIglIYPGggdTYYADSFKGRFTITrdTSKSTAYLQLNSLTSEDTAVY 92

                  ..
gi 1098883676 109 YC 110
Cdd:cd04981    93 YC 94

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        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1098883676  28 QSPSSLSASVGDRVTITCQAsqDISNYLNWYQQKPGKAPKLLIydasnLETGvpsRFSGSGSGTDFTFTISSLQPEDIAT 107
Cdd:cd16096     3 QHPRFAAKKRSSMVKFHCYT--NYSGVMTWFRKKGNQRPQELF-----PEDG---RISQTQNGSVYTLTIQNIQYEDNGI 72

                  ....*
gi 1098883676 108 YYCQQ 112
Cdd:cd16096    73 YFCQQ 77

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        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1098883676  28 QSPSSLSASVGDRVTITCQASQDISN-YLNWYQQKPGKAPKLLIYDasnletgvpsrfsGSGSGTDFTFTISSLQPEDIA 106
Cdd:pfam00047   1 SAPPTVTVLEGDSATLTCSASTGSPGpDVTWSKEGGTLIESLKVKH-------------DNGRTTQSSLLISNVTKEDAG 67

                  ....*
gi 1098883676 107 TYYCQ 111
Cdd:pfam00047  68 TYTCV 72

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        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1098883676  27 TQSPSS-LSASVGDRVTITCQASQDISNYLNWyqqkpgkapklliydasnLETGVP-SRFSGSGSGTDFTFTISSLQPED 104
Cdd:cd20978     4 IQKPEKnVVVKGGQDVTLPCQVTGVPQPKITW------------------LHNGKPlQGPMERATVEDGTLTIINVQPED 65

                  ....*.
gi 1098883676 105 IATYYC 110
Cdd:cd20978    66 TGYYGC 71

Immunoglobulin (Ig)-like domain in the polymeric Ig receptor (pIgR) and similar proteins; The members here are composed of the immunoglobulin (Ig)-like domain in the polymeric Ig receptor (pIgR) and similar proteins. pIgR delivers dimeric IgA and pentameric IgM to mucosal secretions. Polymeric immunoglobulin (pIgs) are the first defense against pathogens and toxins. IgA and IgM can form polymers via an 18-residue extension at their C-termini referred to as the tailpiece. pIgR transports pIgs across mucosal epithelia into mucosal secretions. Human pIgR is a glycosylated type I transmembrane protein, comprised of a 620-residue extracellular region, a 23-residue transmembrane region, and a 103-residue cytoplasmic tail. The extracellular region contains five domains that share sequence similarity with Ig variable (v) regions. This group also contains the Ig-like extracellular domains of other receptors such as NK cell receptor Nkp44 and myeloid receptors, among others.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1098883676  28 QSPSSLSASVGDRVTITCQASQDISNYLNWYQQKPGKAPKLLIydaSNLETGVPSRFSGSGSGTDFTFT--ISSLQPEDI 105
Cdd:cd05716     2 VGPEVVTGVEGGSVTIQCPYPPKYASSRKYWCKWGSEGCQTLV---SSEGVVPGGRISLTDDPDNGVFTvtLNQLRKEDA 78

                          90
                  ....*....|
gi 1098883676 106 ATYYCQQYDN 115
Cdd:cd05716    79 GWYWCGVGDD 88

Immunoglobulin (Ig)-like domain of protein zero (P0) and similar proteins; The members here are composed of the immunoglobulin (Ig) domain of protein zero (P0), a myelin membrane adhesion molecule. P0 accounts for over 50% of the total protein in peripheral nervous system (PNS) myelin. P0 is a single-pass transmembrane glycoprotein with a highly basic intracellular domain and an extracellular Ig domain. The extracellular domain of P0 (P0-ED) is similar to the Ig variable domain, carrying one acceptor sequence for N-linked glycosylation. P0 plays a role in membrane adhesion in the spiral wraps of the myelin sheath. The intracellular domain is thought to mediate membrane apposition of the cytoplasmic faces and may, through electrostatic interactions, interact directly with lipid headgroups. It is thought that homophilic interactions of the P0 extracellular domain mediate membrane juxtaposition in the extracellular space of PNS myelin. This group also contains the Ig domain of sodium channel subunit beta-2 (SCN2B), and of epithelial V-like antigen 1 (EVA). EVA, also known as myelin protein zero-like 2, is an adhesion molecule, which may play a role in structural organization of the thymus and early lymphocyte development. SCN2B subunits play a role in determining sodium channel density and function in neurons,and in control of electrical excitability in the brain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1098883676  30 PSSLSASVGDRVTITCQ------ASQDISnyLNWYQQKPGKAPKLLIYDASNLE--TGVPSRF------SGSGSGTDFTF 95
Cdd:cd05715     6 PRELNVLNGSDVRLTCTftscytVGDAFS--VTWTYQPEGGNTTESMFHYSKGKpyILKVGRFkdrvswAGNPSKKDASI 83

                          90
                  ....*....|....*.
gi 1098883676  96 TISSLQPEDIATYYCQ 111
Cdd:cd05715    84 VISNLQFSDNGTYTCD 99