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 230581     3 QLVQSGGGVVQPGRSLRLSCSSSGFIFSSYAMYWVRQAPGKGLEWVAIIWDDGSDQHYADSVKGRFTISRNDSKNTLFLQ 82
Cdd:cd04981   1 QLQESGPGLVKPGQSLKLSCKASGFTFTSYGMGWVRQAPGKGLEWIGLIYPGGGDTYYADSFKGRFTITRDTSKSTAYLQ 80

                        90       100       110       120
                ....*....|....*....|....*....|....*....|...
gi 230581    83 MDSLRPEDTGVYFCARDGGHGfcssaSCFGPDYWGQGTPVTVS 125
Cdd:cd04981  81 LNSLTSEDTAVYYCARGLGGY-----GYSYFDYWGQGTTVTVS 118

CH1 domain (first constant Ig domain of the heavy chain) in immunoglobulin heavy epsilon and gamma chain; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the first immunoglobulin constant-1 set domain of epsilon and gamma chains. It belongs to a family composed of the first immunoglobulin constant-1 set domain of alpha, delta, epsilon, gamma, and mu heavy chains. This domain is found on the Fab antigen-binding fragment. 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 is composed of a constant domain and a variable domain. There are five types of heavy chains: alpha, delta, epsilon, gamma, and mu, all consisting of a variable domain (VH) with three (alpha, delta and gamma) or four (epsilon and mu) constant domains (CH1 to CH4). Ig molecules are modular proteins, in which the variable and constant domains have clear, conserved sequence patterns. This group belongs to the C1-set of IgSF domains, which are classical Ig-like domains resembling the antibody constant domain. C1-set domains are found almost exclusively in molecules involved in the immune system, such as in immunoglobulin light and heavy chains, in the major histocompatibility complex (MHC) class I and II complex molecules, and in various T-cell receptors.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   131 GPSVFPLAPSSKSTSGGTAALGCLVKDYFPQPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICN 210
Cdd:cd21817   1 APSVFPLAPCCKSTNGSSVTLGCLVTGYFPEPVTVTWNSGSLTSGVKTFPAVLQSSGLYTTSSQVTVPSSSWGSQTFTCN 80

                        90
                ....*....|....
gi 230581   211 VNHKPSNTKVDKRV 224
Cdd:cd21817  81 VEHKPSSTKVDKKI 94

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 230581     3 QLVQSGGGVVQPGRSLRLSCSSSGFIFSSYAMYWVRQAPGKGLEWVAIIWDDGSDQHYADSVKGRFTISRNDSKNTLFLQ 82
Cdd:cd04981   1 QLQESGPGLVKPGQSLKLSCKASGFTFTSYGMGWVRQAPGKGLEWIGLIYPGGGDTYYADSFKGRFTITRDTSKSTAYLQ 80

                        90       100       110       120
                ....*....|....*....|....*....|....*....|...
gi 230581    83 MDSLRPEDTGVYFCARDGGHGfcssaSCFGPDYWGQGTPVTVS 125
Cdd:cd04981  81 LNSLTSEDTAVYYCARGLGGY-----GYSYFDYWGQGTTVTVS 118

CH1 domain (first constant Ig domain of the heavy chain) in immunoglobulin heavy epsilon and gamma chain; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the first immunoglobulin constant-1 set domain of epsilon and gamma chains. It belongs to a family composed of the first immunoglobulin constant-1 set domain of alpha, delta, epsilon, gamma, and mu heavy chains. This domain is found on the Fab antigen-binding fragment. 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 is composed of a constant domain and a variable domain. There are five types of heavy chains: alpha, delta, epsilon, gamma, and mu, all consisting of a variable domain (VH) with three (alpha, delta and gamma) or four (epsilon and mu) constant domains (CH1 to CH4). Ig molecules are modular proteins, in which the variable and constant domains have clear, conserved sequence patterns. This group belongs to the C1-set of IgSF domains, which are classical Ig-like domains resembling the antibody constant domain. C1-set domains are found almost exclusively in molecules involved in the immune system, such as in immunoglobulin light and heavy chains, in the major histocompatibility complex (MHC) class I and II complex molecules, and in various T-cell receptors.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   131 GPSVFPLAPSSKSTSGGTAALGCLVKDYFPQPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICN 210
Cdd:cd21817   1 APSVFPLAPCCKSTNGSSVTLGCLVTGYFPEPVTVTWNSGSLTSGVKTFPAVLQSSGLYTTSSQVTVPSSSWGSQTFTCN 80

                        90
                ....*....|....
gi 230581   211 VNHKPSNTKVDKRV 224
Cdd:cd21817  81 VEHKPSSTKVDKKI 94

Immunoglobulin C1-set domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581     357 VYTLPPSREEMtKNQVSLTCLVKGFYPSDIAVEWESNGQPE-NNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCS 435
Cdd:pfam07654   1 VYVFPPSPEEL-GKPNTLTCLVTGFYPPDITVTWLKNGQEVtEGVKTTPPSPNSDWTYQLSSYLTVTPSDWESGDEYTCR 79

                  ....*.
gi 230581     436 VMHEAL 441
Cdd:pfam07654  80 VEHEGL 85

Immunoglobulin V-Type;

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 230581       26 GFIFSSYAMYWVRQAPGKGLEWVAIIWDDGSDQhYADSVKGRFTISRNDSKNTLFLQMDSLRPEDTGVYFCAR 98
Cdd:smart00406  10 GSTFSSYYVSWVRQPPGKGLEWLGYIGSNGSSY-YQESYKGRFTISKDTSKNDVSLTISNLRVEDTGTYYCAV 81

Immunoglobulin C1-set domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581     134 VFPLAPSSKSTsGGTAALGCLVKDYFPQPVTVSW--NSGALTSGVHTFPAVLQSSGLYSLSSV-VTVPSSSLGTQTYICN 210
Cdd:pfam07654   1 VYVFPPSPEEL-GKPNTLTCLVTGFYPPDITVTWlkNGQEVTEGVKTTPPSPNSDWTYQLSSYlTVTPSDWESGDEYTCR 79

                  ....
gi 230581     211 VNHK 214
Cdd:pfam07654  80 VEHE 83

Immunoglobulin C-Type;

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 230581      268 VTCVVVDVSHEDPQVKfnWYVDGVQVH-NAKTKPREQQYNSTYRVVSVLTVLHQNWLDGKEYKCKVSNKALPAP 340
Cdd:smart00407   4 LVCLVSGFYPPDITVT--WLRNGQEVTeGVSTTDPLKNSDGTYFLSSYLTVPASTWESGDVYTCQVTHEGLKEP 75

MHC-like TNF binding protein; Provisional

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581    308 TYRVVSVLTVLHQNWLDGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNqVSLTCLVKGFYPSDIA 387
Cdd:PHA02865 154 GFPKVGMLTVKSPFWKDVMKYLGSFVYLTCGLTANDYQKMAKGNIPKPVTPTVKVTGEELGDN-TTLFCTFDSHYPSSVA 232

                 ...
gi 230581    388 VEW 390
Cdd:PHA02865 233 AKW 235

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 230581     3 QLVQSGGGVVQPGRSLRLSCSSSGFIFSSYAMYWVRQAPGKGLEWVAIIWDDGSDQHYADSVKGRFTISRNDSKNTLFLQ 82
Cdd:cd04981   1 QLQESGPGLVKPGQSLKLSCKASGFTFTSYGMGWVRQAPGKGLEWIGLIYPGGGDTYYADSFKGRFTITRDTSKSTAYLQ 80

                        90       100       110       120
                ....*....|....*....|....*....|....*....|...
gi 230581    83 MDSLRPEDTGVYFCARDGGHGfcssaSCFGPDYWGQGTPVTVS 125
Cdd:cd04981  81 LNSLTSEDTAVYYCARGLGGY-----GYSYFDYWGQGTTVTVS 118

CH1 domain (first constant Ig domain of the heavy chain) in immunoglobulin heavy epsilon and gamma chain; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the first immunoglobulin constant-1 set domain of epsilon and gamma chains. It belongs to a family composed of the first immunoglobulin constant-1 set domain of alpha, delta, epsilon, gamma, and mu heavy chains. This domain is found on the Fab antigen-binding fragment. 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 is composed of a constant domain and a variable domain. There are five types of heavy chains: alpha, delta, epsilon, gamma, and mu, all consisting of a variable domain (VH) with three (alpha, delta and gamma) or four (epsilon and mu) constant domains (CH1 to CH4). Ig molecules are modular proteins, in which the variable and constant domains have clear, conserved sequence patterns. This group belongs to the C1-set of IgSF domains, which are classical Ig-like domains resembling the antibody constant domain. C1-set domains are found almost exclusively in molecules involved in the immune system, such as in immunoglobulin light and heavy chains, in the major histocompatibility complex (MHC) class I and II complex molecules, and in various T-cell receptors.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   131 GPSVFPLAPSSKSTSGGTAALGCLVKDYFPQPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICN 210
Cdd:cd21817   1 APSVFPLAPCCKSTNGSSVTLGCLVTGYFPEPVTVTWNSGSLTSGVKTFPAVLQSSGLYTTSSQVTVPSSSWGSQTFTCN 80

                        90
                ....*....|....
gi 230581   211 VNHKPSNTKVDKRV 224
Cdd:cd21817  81 VEHKPSSTKVDKKI 94

Immunoglobulin C1-set domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581     357 VYTLPPSREEMtKNQVSLTCLVKGFYPSDIAVEWESNGQPE-NNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCS 435
Cdd:pfam07654   1 VYVFPPSPEEL-GKPNTLTCLVTGFYPPDITVTWLKNGQEVtEGVKTTPPSPNSDWTYQLSSYLTVTPSDWESGDEYTCR 79

                  ....*.
gi 230581     436 VMHEAL 441
Cdd:pfam07654  80 VEHEGL 85

CH1 domain (first constant Ig domain of the heavy chain) in immunoglobulin heavy alpha, delta, epsilon, gamma, and mu chains; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the first immunoglobulin constant-1 set domain of alpha, delta, epsilon, gamma, and mu heavy chains. This domain is found on the Fab antigen-binding fragment. 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 is composed of a constant domain and a variable domain. There are five types of heavy chains: alpha, delta, epsilon, gamma, and mu, all consisting of a variable domain (VH) with three (alpha, delta and gamma) or four (epsilon and mu) constant domains (CH1 to CH4). Ig molecules are modular proteins, in which the variable and constant domains have clear, conserved sequence patterns. This group belongs to the C1-set of IgSF domains, which are classical Ig-like domains resembling the antibody constant domain. C1-set domains are found almost exclusively in molecules involved in the immune system, such as in immunoglobulin light and heavy chains, in the major histocompatibility complex (MHC) class I and II complex molecules, and in various T-cell receptors.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   131 GPSVFPLAPSSKSTSGGTAALGCLVKDYFPQPVTVSW---NSGALTSGVHTFPAVLQSSGLYSLSSVVTV-PSSSLGTQT 206
Cdd:cd04985   1 APTVFPLQSATKSQSNGPVALGCLISDYFPESITVSWqknTNSITSGFTRTFPVVLRSGGDYSCSSQLTVpLQEWNSGEV 80

                        90
                ....*....|....*...
gi 230581   207 YICNVNHKPSNTKVDKRV 224
Cdd:cd04985  81 YKCQVQHSASNSKQEKDV 98

Immunoglobulin Constant-1 (C1)-set domain; The members here are composed of C1-set domains, classical Ig-like domains resembling the antibody constant domain. Members of the IgC1 family are components of immunoglobulin, T-cell receptors, CD1 cell surface glycoproteins, secretory glycoproteins A/C, and major histocompatibility complex (MHC) class I/II molecules. In immunoglobulins, each chain is composed of one variable domain (IgV) and one or more IgC domains. These names reflect the fact that the variability in sequences is higher in the variable domain than in the constant domain. The IgV domain is responsible for antigen binding, while the IgC domain is involved in oligomerization and molecular interactions. 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 strands by G, F, C, and C'.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   356 QVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPEN-NYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSC 434
Cdd:cd00098   1 TVTLLPPSPEEKGGGKVTLVCLVSGFYPKDITVTWLKNGVPLTsGVSTSSPVEPNDGTYSVTSSLTVPPSDWDEGATYTC 80

                ....*..
gi 230581   435 SVMHEAL 441
Cdd:cd00098  81 VVTHESL 87

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 230581    28 IFSSYAMYWVRQAPGKGLEWVAIIwdDGSDQHYADSVKGRFTISRNDSKnTLFLQMDSLRPEDTGVYFCARdgghgfcSS 107
Cdd:cd00099  25 SFSSTYIYWYRQKPGQGPEFLIYL--SSSKGKTKGGVPGRFSGSRDGTS-SFSLTISNLQPEDSGTYYCAV-------SE 94

                        90
                ....*....|....*..
gi 230581   108 ASCFGPDYWGQGTPVTV 124
Cdd:cd00099  95 SGGTDKLTFGSGTRLTV 111

CH2 domain (second constant Ig domain of the heavy chain) in immunoglobulin mu chain; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the second immunoglobulin constant domain (IgC) of mu heavy chains. This domain is found on the Fc fragment. 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 is composed of a constant domain and a variable domain. There are five types of heavy chains: alpha, delta, epsilon, gamma, and mu, all consisting of a variable domain (VH) with three (alpha, delta and gamma) or four (epsilon and mu) constant domains (CH1 to CH4). Ig molecules are modular proteins, in which the variable and constant domains have clear, conserved sequence patterns.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   355 PQVYTLPPSREEMTKNQ-VSLTCLVKGFYPSDIAVEWESNG---QPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGN 430
Cdd:cd16093   2 PTVSLHAPSREEFLGNRtATFVCLATGFSPKTISFKWLRNGkevTSSTGAVVEEPKEDGKTLYSATSFLTITESEWKSQT 81

                        90       100
                ....*....|....*....|.
gi 230581   431 VFSCSVMHEalhNHYTQKSLS 451
Cdd:cd16093  82 EFTCEFKHK---GEIVEKNAS 99

CH3 domain (third constant Ig domain of the heavy chain) in immunoglobulin heavy alpha, gamma, and delta chains, and CH4 domain (fourth constant Ig domain of the heavy chain) in immunoglobulin heavy alpha, epsilon, and mu chains; member of the C1-set of I; The members here are composed of the third and fourth immunoglobulin constant domain (IgC) of alpha, delta, gamma and alpha, epsilon, and mu heavy chains, respectively. This domain is found on the Fc fragment. 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 is composed of a constant domain and a variable domain. There are five types of heavy chains: alpha, delta, epsilon, gamma, and mu, all consisting of a variable domain (VH) with three (alpha, delta and gamma) or four (epsilon and mu) constant domains (CH1 to CH4). Ig molecules are modular proteins, in which the variable and constant domains have clear, conserved sequence patterns.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   247 PSVFLFPPkPKDTLMISRTPEVTCVVVDVSHEDPQVKfnWYVDGVQV--HNAKTKPREQQYNSTYRVVSVLTVLHQNWLD 324
Cdd:cd05768   1 PSVYLLPP-PEEELSLNETVTLTCLVKGFYPEDIFVS--WLQNGEPLpsADYKTTAPVPESDGSFFVYSKLNVSTADWNS 77

                        90       100
                ....*....|....*....|....*...
gi 230581   325 GKEYKCKVSNKALPAP-IEKTISKAKGQ 351
Cdd:cd05768  78 GDVFSCVVGHEALPLQfTQKSIDKSPGK 105

Immunoglobulin Constant-1 (C1)-set domain; The members here are composed of C1-set domains, classical Ig-like domains resembling the antibody constant domain. Members of the IgC1 family are components of immunoglobulin, T-cell receptors, CD1 cell surface glycoproteins, secretory glycoproteins A/C, and major histocompatibility complex (MHC) class I/II molecules. In immunoglobulins, each chain is composed of one variable domain (IgV) and one or more IgC domains. These names reflect the fact that the variability in sequences is higher in the variable domain than in the constant domain. The IgV domain is responsible for antigen binding, while the IgC domain is involved in oligomerization and molecular interactions. 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 strands by G, F, C, and C'.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   248 SVFLFPPKPKDTLmiSRTPEVTCVVVDVSHEDPQVKfnWYVDGVQVHNAKTKPRE-QQYNSTYRVVSVLTVLHQNWLDGK 326
Cdd:cd00098   1 TVTLLPPSPEEKG--GGKVTLVCLVSGFYPKDITVT--WLKNGVPLTSGVSTSSPvEPNDGTYSVTSSLTVPPSDWDEGA 76

                        90
                ....*....|....*....
gi 230581   327 EYKCKVSNKALPAPIEKTI 345
Cdd:cd00098  77 TYTCVVTHESLKSPLSKTW 95

CH1 domain (first constant Ig domain of the heavy chain) in immunoglobulin heavy alpha chain; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the first immunoglobulin constant-1 set domain of alpha chains. It belongs to a family composed of the first immunoglobulin constant-1 set domain of alpha, epsilon, gamma, and mu heavy chains. This domain is found on the Fab antigen-binding fragment. 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 is composed of a constant domain and a variable domain. There are five types of heavy chains: alpha, delta, epsilon, gamma, and mu, all consisting of a variable domain (VH) with three (alpha, delta and gamma) or four (epsilon and mu) constant domains (CH1 to CH4). Ig molecules are modular proteins, in which the variable and constant domains have clear, conserved sequence patterns. This group belongs to the C1-set of IgSF domains, which are classical Ig-like domains resembling the antibody constant domain. C1-set domains are found almost exclusively in molecules involved in the immune system, such as in immunoglobulin light and heavy chains, in the major histocompatibility complex (MHC) class I and II complex molecules, and in various T-cell receptors.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   132 PSVFPLApSSKSTSGGTAALGCLVKDYFPQPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSS-LGTQTYICN 210
Cdd:cd21818   2 PTVFPLS-LCPSLSSDPVVIGCLVQGFFPEPVNVTWNYSGKGGTARNFPAMLASGGRYTQSSQLTLPADQcPEGEAYKCS 80

                ...
gi 230581   211 VNH 213
Cdd:cd21818  81 VQH 83

CH1 domain (first constant Ig domain of the heavy chain) in immunoglobulin heavy mu chain; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the first immunoglobulin constant-1 set domain of mu chains. It belongs to a family composed of the first immunoglobulin constant-1 set domain of alpha, delta, epsilon, gamma, and mu heavy chains. This domain is found on the Fab antigen-binding fragment. 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 is composed of a constant domain and a variable domain. There are five types of heavy chains: alpha, delta, epsilon, gamma, and mu, all consisting of a variable domain (VH) with three (alpha, delta and gamma) or four (epsilon and mu) constant domains (CH1 to CH4). Ig molecules are modular proteins, in which the variable and constant domains have clear, conserved sequence patterns. This group belongs to the C1-set of IgSF domains, which are classical Ig-like domains resembling the antibody constant domain. C1-set domains are found almost exclusively in molecules involved in the immune system, such as in immunoglobulin light and heavy chains, in the major histocompatibility complex (MHC) class I and II complex molecules, and in various T-cell receptors.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   132 PSVFPLAPSSkSTSGGTAALGCLVKDYFPQPVTVSWNSG--ALTSGVHTFPAVLqSSGLYSLSSVVTVPSSSLGTQTYI- 208
Cdd:cd21819   2 PTLFPLVSCG-SSTSDPVTVGCLATDFLPDSITFSWTDDnnSLTTGVKTYPSVL-TGGTYTASSQLQVPESEWKSKENFy 79

                        90
                ....*....|...
gi 230581   209 CNVNHKPSNTKVD 221
Cdd:cd21819  80 CKVEHPGGNKEVP 92

CH1 domain (first constant Ig domain of the heavy chain) in immunoglobulin heavy alpha, delta, epsilon, gamma, and mu chains; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the first immunoglobulin constant-1 set domain of alpha, delta, epsilon, gamma, and mu heavy chains. This domain is found on the Fab antigen-binding fragment. 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 is composed of a constant domain and a variable domain. There are five types of heavy chains: alpha, delta, epsilon, gamma, and mu, all consisting of a variable domain (VH) with three (alpha, delta and gamma) or four (epsilon and mu) constant domains (CH1 to CH4). Ig molecules are modular proteins, in which the variable and constant domains have clear, conserved sequence patterns. This group belongs to the C1-set of IgSF domains, which are classical Ig-like domains resembling the antibody constant domain. C1-set domains are found almost exclusively in molecules involved in the immune system, such as in immunoglobulin light and heavy chains, in the major histocompatibility complex (MHC) class I and II complex molecules, and in various T-cell receptors.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   355 PQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEW--ESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVF 432
Cdd:cd04985   2 PTVFPLQSATKSQSNGPVALGCLISDYFPESITVSWqkNTNSITSGFTRTFPVVLRSGGDYSCSSQLTVPLQEWNSGEVY 81

                ....*...
gi 230581   433 SCSVMHEA 440
Cdd:cd04985  82 KCQVQHSA 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
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581    29 FSSYAMYWVRQAPGKGLEWVAIIWDDGSDQHYADSVKGRFTISRNDSKNTLFLQMDSLRPEDTGVYFCAR 98
Cdd:cd04982  27 FSTTYIHWYRQKPGQALERLLYVSSTSAVRKDSGKTKNKFEARKDVGKSTSTLTITNLEKEDSATYYCAY 96

Signal-regulatory protein (SIRP) immunoglobulin-like domain 3; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the immunoglobulin (Ig)-like domain in Signal-Regulatory Protein (SIRP), domain 3 (C1 repeat 2). The SIRPs belong to the "paired receptors" class of membrane proteins that comprise several genes coding for proteins with similar extracellular regions but very different transmembrane/cytoplasmic regions with different (activating or inhibitory) signaling potentials. They are commonly on NK cells, but are also on many myeloid cells. Their extracellular region contains three Immunoglobulin superfamily domains a single V-set and two C1-set IgSF domains. Their cytoplasmic tails that contain either ITIMs or transmembrane regions that have positively charged residues that allow an association with adaptor proteins, such as DAP12/KARAP, containing ITAMs. There are 3 distinct SIRP members: alpha, beta, and gamma. SIRP alpha (also known as CD172a or SRC homology 2 domain-containing protein tyrosine phosphatase substrate 1/Shps-1) is a membrane receptor that interacts with a ligand CD47 expressed on many cells and gives an inhibitory signal through immunoreceptor tyrosine-based inhibition motifs in the cytoplasmic region that interact with phosphatases SHP-1 and SHP-2. SIRP beta has a short cytoplasmic region and associates with a transmembrane adapter protein DAP12 containing immunoreceptor tyrosine-based activation motifs to give an activating signal. SIRP gamma contains a very short cytoplasmic region lacking obvious signaling motifs but also binds CD47, but with much less affinity.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 230581   367 MTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHE 439
Cdd:cd16085  13 MVWNQVNVTCQVEKFYPQRLQLTWLENGNVSRTETPSTLTVNKDGTYNWTSWLLVNVSAHREDVVLTCQVEHD 85

Immunoglobulin domain of Cluster of Differentiation (CD) 1; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the immunoglobulin domain of Cluster of Differentiation (CD) 1. CD1 family of transmembrane glycoproteins, are structurally related to the major histocompatibility complex (MHC) proteins and form heterodimers with beta-2-microglobulin. They mediate the presentation of primarily lipid and glycolipid antigens of self or microbial origin to T cells. The human genome contains five CD1 family genes (CD1a, CD1b, CD1c, CD1d, and CD1e) organized in a cluster on chromosome 1. The CD1 family members are thought to differ in their cellular localization and specificity for particular lipid ligands. CD1a localizes to the plasma membrane and to recycling vesicles of the early endocytic system. Alternative splicing results in multiple transcript variants. Immunoglobulin (Ig) domain of major histocompatibility complex (MHC) class I alpha chain. Class I MHC proteins bind antigenic peptide fragments and present them to CD8+ T lymphocytes. Class I molecules consist of a transmembrane alpha chain and a small chain called the beta-2-microglobulin. The alpha chain contains three extracellular domains, two of which fold together to form the peptide-binding cleft (alpha1 and alpha2), and one which has an Ig fold (alpha3). Peptide binding to class I molecules occurs in the endoplasmic reticulum (ER) and involves both chaperones and dedicated factors to assist in peptide loading. Class I MHC molecules are expressed on most nucleated cells. C1-set Ig domains have one beta sheet that is formed by strands A, B, E, and D and the other strands by G, F, C, and C'.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   363 SREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL-DSDGSFFLYSKLTVDKsrwQQGNVFSCSVMHEAL 441
Cdd:cd21029   9 SRPSPGDGHLQLSCHVTGFYPRPIEVTWLRDGQEQMDGTQSGGILpNHDGTYQLRKTLDIAP---GEGAGYSCRVDHSSL 85

Immunoglobulin Constant-1 (C1)-set domain; The members here are composed of C1-set domains, classical Ig-like domains resembling the antibody constant domain. Members of the IgC1 family are components of immunoglobulin, T-cell receptors, CD1 cell surface glycoproteins, secretory glycoproteins A/C, and major histocompatibility complex (MHC) class I/II molecules. In immunoglobulins, each chain is composed of one variable domain (IgV) and one or more IgC domains. These names reflect the fact that the variability in sequences is higher in the variable domain than in the constant domain. The IgV domain is responsible for antigen binding, while the IgC domain is involved in oligomerization and molecular interactions. 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 strands by G, F, C, and C'.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   133 SVFPLAPSSKSTSGGTAALGCLVKDYFPQPVTVSW--NSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQ-TYIC 209
Cdd:cd00098   1 TVTLLPPSPEEKGGGKVTLVCLVSGFYPKDITVTWlkNGVPLTSGVSTSSPVEPNDGTYSVTSSLTVPPSDWDEGaTYTC 80

                        90
                ....*....|....*
gi 230581   210 NVNHKPSNTKVDKRV 224
Cdd:cd00098  81 VVTHESLKSPLSKTW 95

CH2 domain (second constant Ig domain of the heavy chain) in immunoglobulin E (IgE); member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the second constant domain of the heavy chain of immunoglobulin E (IgE). The basic structure of immunoglobulin (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 is composed of a constant domain and a variable domain. There are five types of heavy chains: alpha, delta, epsilon, gamma, and mu, all consisting of a variable domain (VH) with three (alpha, delta, and gamma) or four (epsilon and mu) constant domains (CH1 to CH4). The different classes of antibodies vary in their heavy chains; the IgE class has the epsilon type. This domain (Cepsilon2) of IgE is in place of the flexible hinge region found in IgG.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   247 PSVFLFPPKPKDTLMiSRTPEVTCVVVdvSHEDPQVKFNWYVDGVQVHN--AKTKPREQQyNSTYRVVSVLTVLHQNWLD 324
Cdd:cd05847   1 PTVQILHSSCASTLT-SETIQLLCLIS--GYTPSTIEVEWLVDGQVATLsaASTAPQKEE-GGTFSTTSKLNVTQEDWKS 76

                        90
                ....*....|...
gi 230581   325 GKEYKCKVSNKAL 337
Cdd:cd05847  77 GKTYTCKVTHQGT 89

Class II major histocompatibility complex (MHC) beta chain immunoglobulin domain of histocompatibility antigen (HLA) DQ and I-A; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the Class II major histocompatibility complex (MHC) beta chain immunoglobulin domain of human histocompatibility antigen (HLA) DQ and mouse I-A. Three genetically distinct isotypes of class II MHC molecules are found in humans (HLA-DR, HLA-DQ, and HLA-DP), and two in mice (I-E and I-A). I-A and I-E have the same basic features insofar as peptide loading and presentation, they differ in that each interacts with distinctly different sets of peptides, and in the incidence of deletion of their genes. A structural understanding of the similarities and differences between I-A and I-E may help with understanding their roles in peptide presentation and T cell activation. Mouse I-Ag7 has a genetic susceptibility to autoimmune diabetes due to its small, uncharged amino acid residue at position 57 of their beta chain which results in the absence of a salt bridge between beta 57 and Arg alpha 76, which is adjacent to the P9 pocket of the peptide-binding groove. Human HLA-DR, -DQ, and -DP are about 70% similar to each other. HLA-DQ (DQ) is a cell surface receptor protein found on antigen presenting cells. It is an alphabeta heterodimer of type MHC class II. The alpha and beta chains are encoded by two loci, HLA-DQA1 and HLA-DQB1, that are adjacent to each other on chromosome band 6p21.3. A person often produces two alpha-chain and two beta chain variants and thus 4 isoforms of DQ. HLA-DQ is involved in the autoimmune diseases celiac disease and diabetes mellitus type. DQ is one of several antigens involved in rejection of organ transplants. DQ2 is encoded by the HLA-DQB1*02 allele group. DQ6 is encoded by the HLA-DQB1*06 allele group. DQ2 beta-chains combine with alpha-chains, encoded by genetically linked HLA-DQA1 alleles, to form the cis-haplotype isoforms. These isoforms, nicknamed DQ2.2 and DQ2.5, are also encoded by the DQA1*0201 and DQA1*0501 genes, respectively. DQ6 beta-chains combine with alpha-chains, encoded by genetically linked HLA-DQA1 alleles, to form the cis-haplotype isoforms. For DQ6, however, cis-isoform pairing only occurs with DQ1 alpha-chains. There are many haplotypes of DQ6. Susceptibility to Leptospirosis infection was found associated with undifferentiated DQ6. DQ8 is determined by the antibody recognition of beta8 and this generally detects the gene product of DQB1*0302. DQ8 is commonly linked to autoimmune disease in the human population. DQ8 is the second most predominant isoform linked to celiac disease and the DQ most linked to Type 1 diabetes. DQ8 increases the risk for rheumatoid arthritis and is linked to the primary risk locus for RA, HLA-DR4. DR4 also plays an important role in Type 1 diabetes. DQ8 is a split antigen of the DQ3 broad antigen. MHC class II molecules play a key role in the initiation of the antigen-specific immune response. They are expressed constitutively on the cell surface of professional antigen-presenting cells (APCs), including B-lymphocytes, monocytes, and macrophages in both humans and mice, and induced in nonprofessional APCs, such as keratinocyctes; they are expressed on the surface of activated human T cells and on T cells from other species. MHC II molecules present antigenic peptides to CD4(+) T-lymphocytes; these peptides derive mostly from proteolytic processing via the endocytic pathway, of antigens internalized by the APC, and bind to the MHC class II molecules in the endosome before they are transported to the cell surface. MHC class II molecules are heterodimers, comprised of two similarly-sized membrane-spanning chains, alpha and beta. Each chain had two globular domains (N- and C-terminal), and a membrane-anchoring transmembrane segment. The two chains form a compact four-domain structure. The peptide-binding site is a cleft in the structure.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   354 EPQVyTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPEN-NYKTTPPVLDSDGSFFLYSKLTVDKsrwQQGNVF 432
Cdd:cd21001   3 EPTV-TISPSRTEALNHHNLLVCSVTDFYPGQIKVRWFRNDQEETaGVVSTPLIRNGDWTFQILVMLEMTP---QRGDVY 78

                ....*....
gi 230581   433 SCSVMHEAL 441
Cdd:cd21001  79 TCHVEHPSL 87

CH1 domain (first constant Ig domain of the heavy chain) in immunoglobulin heavy alpha chain; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the first immunoglobulin constant-1 set domain of alpha chains. It belongs to a family composed of the first immunoglobulin constant-1 set domain of alpha, epsilon, gamma, and mu heavy chains. This domain is found on the Fab antigen-binding fragment. 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 is composed of a constant domain and a variable domain. There are five types of heavy chains: alpha, delta, epsilon, gamma, and mu, all consisting of a variable domain (VH) with three (alpha, delta and gamma) or four (epsilon and mu) constant domains (CH1 to CH4). Ig molecules are modular proteins, in which the variable and constant domains have clear, conserved sequence patterns. This group belongs to the C1-set of IgSF domains, which are classical Ig-like domains resembling the antibody constant domain. C1-set domains are found almost exclusively in molecules involved in the immune system, such as in immunoglobulin light and heavy chains, in the major histocompatibility complex (MHC) class I and II complex molecules, and in various T-cell receptors.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   355 PQVY--TLPPSReemTKNQVSLTCLVKGFYPSDIAVEWESNGQpENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVF 432
Cdd:cd21818   2 PTVFplSLCPSL---SSDPVVIGCLVQGFFPEPVNVTWNYSGK-GGTARNFPAMLASGGRYTQSSQLTLPADQCPEGEAY 77

                ....*.
gi 230581   433 SCSVMH 438
Cdd:cd21818  78 KCSVQH 83

Class I major histocompatibility complex (MHC) alpha chain, alpha3 immunoglobulin domain; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the immunoglobulin (Ig) domain of major histocompatibility complex (MHC) class I alpha chain. Class I MHC proteins bind antigenic peptide fragments and present them to CD8+ T lymphocytes. Class I molecules consist of a transmembrane alpha chain and a small chain called the beta-2-microglobulin. The alpha chain contains three extracellular domains, two of which fold together to form the peptide-binding cleft (alpha1 and alpha2), and one which has an Ig fold (alpha3). Peptide binding to class I molecules occurs in the endoplasmic reticulum (ER) and involves both chaperones and dedicated factors to assist in peptide loading. Class I MHC molecules are expressed on most nucleated cells.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   361 PPS----REEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVL-DSDGSFFLYSKLTVDKSRWQqgnVFSCS 435
Cdd:cd07698   2 PPKvhvtHHPRSDGESTLRCWALGFYPAEITLTWQRDGEDQTQDMELVETRpNGDGTFQKWAAVVVPSGEEQ---RYTCH 78

                        90
                ....*....|.
gi 230581   436 VMHEALHNHYT 446
Cdd:cd07698  79 VQHEGLPEPLT 89

Class II major histocompatibility complex (MHC) beta chain immunoglobulin domain; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the immunoglobulin (Ig) domain of major histocompatibility complex (MHC) class II beta chain. MHC class II molecules play a key role in the initiation of the antigen-specific immune reponse. These molecules have been shown to be expressed constitutively on the cell surface of professional antigen-presenting cells (APCs), including B-lymphocytes, monocytes, and macrophages in both humans and mice. The expression of these molecules has been shown to be induced in nonprofessional APCs such as keratinocyctes and they are also expressed on the surface of activated human T cells and on T cells from other species. The MHC II molecules present antigenic peptides to CD4(+) T-lymphocytes. These peptides derive mostly from proteolytic processing via the endocytic pathway of antigens internalized by the APC. These peptides bind to the MHC class II molecules in the endosome before they are transported to the cell surface. MHC class II molecules are heterodimers, comprised of two similarly-sized membrane-spanning chains, alpha and beta. Each chain has two globular domains (N- and C-terminal) and a membrane-anchoring transmembrane segment. The two chains form a compact four-domain structure. The peptide-binding site is a cleft in the structure.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 230581   353 REPQVyTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPEN---NYKTTPPVLDsdgsfFLYSKLTVDKSRWQQG 429
Cdd:cd05766   2 VQPSV-KVSPTKTGPLEHPNLLVCSVTGFYPAEIEVKWFRNGQEETagvVSTELIPNGD-----WTFQILVMLETTPRRG 75

                        90
                ....*....|..
gi 230581   430 NVFSCSVMHEAL 441
Cdd:cd05766  76 DVYTCQVEHSSL 87