Immunoglobulin C1-set domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 204797       7 VSIFPPSSEQLaTGGASVVCFINNFYPKDISVKWKIDGSERQNDVLNSvTDQDSKDSTYSMSSTLTLTKADYESHNLFVC 86
Cdd:pfam07654   1 VYVFPPSPEEL-GKPNTLTCLVTGFYPPDITVTWLKNGQEVTEGVKTT-PPSPNSDWTYQLSSYLTVTPSDWESGDEYTC 78

                  ....*..
gi 204797      87 EVVHKTS 93
Cdd:pfam07654  79 RVEHEGL 85

Immunoglobulin C1-set domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 204797       7 VSIFPPSSEQLaTGGASVVCFINNFYPKDISVKWKIDGSERQNDVLNSvTDQDSKDSTYSMSSTLTLTKADYESHNLFVC 86
Cdd:pfam07654   1 VYVFPPSPEEL-GKPNTLTCLVTGFYPPDITVTWLKNGQEVTEGVKTT-PPSPNSDWTYQLSSYLTVTPSDWESGDEYTC 78

                  ....*..
gi 204797      87 EVVHKTS 93
Cdd:pfam07654  79 RVEHEGL 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 204797     6 TVSIFPPSSEQLATGGASVVCFINNFYPKDISVKWKIDGSERQNDVLNSVTdQDSKDSTYSMSSTLTLTKADYESHNLFV 85
Cdd:cd00098   1 TVTLLPPSPEEKGGGKVTLVCLVSGFYPKDITVTWLKNGVPLTSGVSTSSP-VEPNDGTYSVTSSLTVPPSDWDEGATYT 79

                        90
                ....*....|....*.
gi 204797    86 CEVVHKTSASPIVKSF 101
Cdd:cd00098  80 CVVTHESLKSPLSKTW 95

T cell receptor (TCR) beta chain constant immunoglobulin domain; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the T cell receptor (TCR) beta chain constant immunoglobulin domain. 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 beta chain. Alpha/beta TCRs recognize antigen as peptide fragments presented by major histocompatibility complex (MHC) molecules. The antigen binding site is formed by the variable domains of the alpha and beta chains, located at the N-terminus of each chain. Alpha/beta TCRs recognize antigens differently from gamma/delta TCRs.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 204797     4 VPTVSIFPPSS-EQLATGGASVVCFINNFYPKDISVKWKIDGSERQNDVlnsVTDQDSK---DSTYSMSSTLTLTKADYE 79
Cdd:cd05769   2 PPTVALFPPSEaEIRNKRKATLVCLATGFYPDHVSLSWKVNGKEVKDGV---ATDPQALrenTSTYSLSSRLRVSATEWF 78

                        90
                ....*....|..
gi 204797    80 S-HNLFVCEVVH 90
Cdd:cd05769  79 NpRNTFTCIVKF 90

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 204797     5 PTVSIFPPSSEQLATGGA-SVVCFINNFYPKDISVKWKIDGSERQNDVLNSVTDQDSkDSTYSMSSTLTLTKADYESHNL 83
Cdd:cd05847   1 PTVQILHSSCASTLTSETiQLLCLISGYTPSTIEVEWLVDGQVATLSAASTAPQKEE-GGTFSTTSKLNVTQEDWKSGKT 79

                ....*..
gi 204797    84 FVCEVVH 90
Cdd:cd05847  80 YTCKVTH 86

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        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 204797    10 FPPS---SEQLATGG--ASVVCFINNFYPKDISVKWKIDGSERQNDVLNSVTDqdSKDSTYSMSSTLTLTKADYESHNLF 84
Cdd:cd16085   1 VPPTlevTQQPTMVWnqVNVTCQVEKFYPQRLQLTWLENGNVSRTETPSTLTV--NKDGTYNWTSWLLVNVSAHREDVVL 78

                ....*.
gi 204797    85 VCEVVH 90
Cdd:cd16085  79 TCQVEH 84

Class II major histocompatibility complex (MHC) beta chain immunoglobulin domain of histocompatibility antigen (HLA) DR; 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 histocompatibility antigen (HLA) DR. HLA-DR is an MHC class II cell surface receptor encoded by the human leukocyte antigen complex on chromosome 6 region 6p21.31. HLA-DR is also involved in several autoimmune conditions, disease susceptibility, and disease resistance including seronegative-rheumatoid arthritis, penicillamine-induced myasthenia, schizophrenia, Goodpasture syndrome, systemic lupus erythematosus, Alzheimers, tuberculoid leprosy, and Hashimoto's thyroiditis. HLA-DR molecules are upregulated in response to signaling. HLA-DR is an alphabeta heterodimer cell surface receptor, each subunit of which contains two extracellular domains, a membrane-spanning domain, and a cytoplasmic tail. Both alpha and beta chains are anchored in the membrane. The DR beta chain is encoded by 4 loci, however no more than 3 functional loci are present in a single individual, and no more than two on a single chromosome. Sometimes an individual may only possess 2 copies of the same locus, DRB1*. The HLA-DRB1 locus is ubiquitous and encodes a very large number of functionally variable gene products (HLA-DR1 to HLA-DR17). The HLA-DRB3 locus encodes the HLA-DR52 specificity, is moderately variable and is variably associated with certain HLA-DRB1 types. The HLA-DRB4 locus encodes the HLA-DR53 specificity, has some variation, and is associated with certain HLA-DRB1 types. The HLA-DRB5 locus encodes the HLA-DR51 specificity, which is typically invariable, and is linked to the HLA-DR2 types. 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). 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 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 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 204797     5 PTVSIFPPSSEQLATGGAsVVCFINNFYPKDISVKWKIDGSERQNDVLNSVTDQDSkDSTYsmsSTLTLTKADYESHNLF 84
Cdd:cd21000   4 PKVTVYPAKTQPLQHHNL-LVCSVNGFYPGSIEVRWFRNGQEEKAGVVSTGLIQNG-DWTF---QTLVMLETVPRSGEVY 78

                        90
                ....*....|...
gi 204797    85 VCEVVHKTSASPI 97
Cdd:cd21000  79 TCQVEHPSVTSPL 91

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 204797     5 PTVSIFppSSEQLATGGASVVCFINNFYPKDISVKWKIDGSERQNDVlNSVTDQDSKDSTYSMSSTLTLTKADYESHNlf 84
Cdd:cd21029   3 PRVRLS--SRPSPGDGHLQLSCHVTGFYPRPIEVTWLRDGQEQMDGT-QSGGILPNHDGTYQLRKTLDIAPGEGAGYS-- 77

                        90
                ....*....|....
gi 204797    85 vCEVVHKTSASPIV 98
Cdd:cd21029  78 -CRVDHSSLKQDLI 90

Class II major histocompatibility complex (MHC) beta chain immunoglobulin domain of histocompatibility antigen (HLA) I-E; 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 histocompatibility antigen (HLA) I-E. 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 molecules have the same basic features insofar as peptide loading and presentation, although each interacts with distinctly different sets of peptides. They also differ in that there is a relatively high incidence of deletion of the I-E gene in both inbred strains of mice as well as wild mice and the lack of the reverse situation i.e. the deletion of I-A genes. A detailed structural understanding of the similarities and differences between I-A and the paralogous I-E could help illuminate the respective roles these molecules play 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. 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 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 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 204797     5 PTVSIFPPSSEQLATGGAsVVCFINNFYPKDISVKWKIDGSERQNDVLNSVTDQDSkDSTYsmsSTLTLTKADYESHNLF 84
Cdd:cd20998   7 PTVTVYPTKTQPLEHHNL-LVCSVSDFYPGNIEVRWFRNGKEEKTGIVSTGLVRNG-DWTF---QTLVMLETVPQSGEVY 81

                        90
                ....*....|...
gi 204797    85 VCEVVHKTSASPI 97
Cdd:cd20998  82 TCQVEHPSLTDPV 94

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 204797     5 PTVSIFPPSSEQLATGgasvvCFINNFYPKDISVKWKIDGSERQNDVLN--SVTdqdsKDSTYSMSSTLTLTKADYESHN 82
Cdd:cd21819   6 PLVSCGSSTSDPVTVG-----CLATDFLPDSITFSWTDDNNSLTTGVKTypSVL----TGGTYTASSQLQVPESEWKSKE 76

                ....*...
gi 204797    83 LFVCEVVH 90
Cdd:cd21819  77 NFYCKVEH 84

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 204797     5 PTVSIF-PPSSEqlatGGASVVCFINNFYPKDISVKWKIDGSERQNDVLnSVTDQDSKDSTYSMSSTLTLtkaDYESHNL 83
Cdd:cd07698   3 PKVHVThHPRSD----GESTLRCWALGFYPAEITLTWQRDGEDQTQDME-LVETRPNGDGTFQKWAAVVV---PSGEEQR 74

                        90
                ....*....|....*
gi 204797    84 FVCEVVHKTSASPIV 98
Cdd:cd07698  75 YTCHVQHEGLPEPLT 89

T cell receptor (TCR) gamma chain constant immunoglobulin domain; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the immunoglobulin (Ig) constant (C) 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 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.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 204797     5 PTVSIFPPSS-EQLATGGASVVCFINNFYPKDISVKWKIDGSerqNDVLNSVTDQDSKDS-TYSMSSTLTLTKADYEshN 82
Cdd:cd07697   2 PKPTIFLPSIaETEKQKAGTYLCLLENFFPDVIKIHWREKKS---DTILESQEGNTEKTKdTYMKFSWLTVPKKSLG--K 76

                ....*....
gi 204797    83 LFVCEVVHK 91
Cdd:cd07697  77 EHRCIYKHE 85

Class II major histocompatibility complex (MHC) alpha chain immunoglobulin domain; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the immunoglobulin (Ig) domain of the major histocompatibility complex (MHC) class II alpha 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 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
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 204797    25 VCFINNFYPKDISVKWKIDGSErqndVLNSVTDQD---SKDSTYSMSSTLTLTKadyESHNLFVCEVVHKTSASPIVK 99
Cdd:cd05767  22 ICFVDNFFPPVINVTWLRNGQP----VTDGVSETVflpREDHSFRKFSYLPFTP---SEGDIYDCRVEHWGLEEPLLK 92

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 204797     8 SIFP--PSSEQLATGGASVVCFINNFYPKDISVKWKIDGSERQNDVLNSVTDQdskDSTYSMSSTLTLTKADYEShNLFV 85
Cdd:cd21817   3 SVFPlaPCCKSTNGSSVTLGCLVTGYFPEPVTVTWNSGSLTSGVKTFPAVLQS---SGLYTTSSQVTVPSSSWGS-QTFT 78

                        90
                ....*....|....
gi 204797    86 CEVVHKTSASPIVK 99
Cdd:cd21817  79 CNVEHKPSSTKVDK 92

Class Ia major histocompatibility complex (MHC) immunoglobulin domain of RT1-Aa; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the Class Ia major histocompatibility complex (MHC) immunoglobulin domain of RT1-Aa. While most mammalian species transport these peptides into the ER via a single allele of TAP, rats have evolved different TAPs, TAP-A and TAP-B, RT1-Aa and RT1-A1c, which are associated with TAP-A and TAP-B. The rat MHC class Ia molecule RT1-Aa has the unusual capacity to bind long peptides ending in arginine, such as MTF-E, a thirteen-residue, maternally transmitted minor histocompatibility antigen. 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
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 204797    20 GGASVVCFINNFYPKDISVKWKIDGSERQNDvLNSVTDQDSKDSTYSMSSTLTLTKADYEShnlFVCEVVHKTSASPI 97
Cdd:cd21015  17 GDVTLRCWALGFYPADITLTWQLNGEDLTQD-MELVETRPAGDGTFQKWASVVVPLGKEQN---YTCRVEHEGLPKPL 90

Class Ib major histocompatibility complex (MHC) immunoglobulin domain of Qa-1 and similar proteins; member of the C1-set of Ig superfamily (IgSF) domains; Class Ib major histocompatibility complex (MHC) immunoglobulin domain of Qa-1 and similar proteins. Qa-1 presents hydrophobic peptides including Qdm derived from the leader sequence of classical MHC I molecules for immune surveillance by NK cells. Qa-1 bound peptides derived from the TCR Vbeta8.2 of activated T cells also activates CD8+ regulatory T cells to control autoimmunity and maintain self-tolerance. Four allotypes of Qa-1 (Qa-1a-d) are expressed that are highly conserved in sequence but have several variations that could affect peptide binding to Qa-1 or TCR recognition. 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 204797    12 PSSEqlatGGASVVCFINNFYPKDISVKWKIDGSERQNDvLNSVTDQDSKDSTYSMSSTLTLTKADYEShnlFVCEVVHK 91
Cdd:cd21013  13 PRSE----GYVTLRCWALGFYPADITLTWQLNGEELTQD-MEFVETRPAGDGTFQKWASVVVPLGKEQK---YTCHVEHE 84

                ....*.
gi 204797    92 TSASPI 97
Cdd:cd21013  85 GLPEPL 90

Class Ia major histocompatibility complex (MHC) immunoglobulin domain of human leukocyte antigen (HLA) B and similar proteins; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the class Ia major histocompatibility complex (MHC) immunoglobulin domain of human leukocyte antigen (HLA) B and similar proteins. The classical class I molecules (HLA-A, -B, and -C) are responsible for the presentation of endogenous antigen to CD8+ T cells. The receptor is a heterodimer, and is composed of a heavy alpha chain and smaller beta chain. The alpha chain is encoded by a variant HLA-B gene, and the beta chain (beta-2-microglobulin) is an invariant beta-2-microglobulin molecule. The beta-2-microglobulin protein is coded for by a separate region of the human genome. Human leukocyte antigen (HLA) B*3501 (B35) is a common human allele involved in mediating protective immunity against HIV. 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
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 204797    22 ASVVCFINNFYPKDISVKWKIDGSERQNDVlNSVTDQDSKDSTYSMSSTLTLTKADYEShnlFVCEVVHKTSASPI 97
Cdd:cd21026  20 ATLRCWALGFYPAEITLTWQRDGEDQTQDT-ELVETRPAGDRTFQKWAAVVVPSGEEQR---YTCHVQHEGLPKPL 91

Class Ib major histocompatibility complex (MHC) immunoglobulin domain of human leukocyte antigen (HLA) G; member of the C1-set of Ig superfamily (IgSF) domains; The members here are composed of the Class Ib major histocompatibility complex (MHC) immunoglobulin domain of human leukocyte antigen (HLA) G. HLA-G histocompatibility antigen (also known as human leukocyte antigen G ; HLA-G) is a protein that in humans is encoded by the HLA-G gene. HLA-G belongs to the HLA nonclassical class I heavy chain paralogs. This class I molecule is a heterodimer consisting of a heavy chain and light chain, beta-2-microglobulin. The heavy chain is anchored in the membrane. HLA-G may play a role in immune tolerance in pregnancy, being expressed in the placenta by extravillous trophoblast cells (EVT), while the classical MHC class I genes (HLA-A and HLA-B) are not. Immunoglobulin (Ig) domain of major histocompatibility complex (MHC) class I and class II. 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. MHC class II molecules play a key role in the initiation of the antigen-specific immune repose. 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 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 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.

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                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 204797    22 ASVVCFINNFYPKDISVKWKIDGSERQNDVlNSVTDQDSKDSTYSMSSTLTLTKADYEShnlFVCEVVHKTSASPIV 98
Cdd:cd21022  19 ATLRCWALGFYPAEIILTWQRDGEDQTQDV-ELVETRPAGDGTFQKWAAVVVPSGEEQR---YTCHVQHEGLPEPLM 91

Class II major histocompatibility complex (MHC) alpha chain immunoglobulin domain of histocompatibility antigen (HLA) I-A; 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 alpha chain of histocompatibility antigen (HLA) 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 molecules have the same basic features insofar as peptide loading and presentation, although each interacts with distinctly different sets of peptides. They also differ in that there is a relatively high incidence of deletion of the I-E a gene in both inbred strains of mice as well as wild mice and the lack of the reverse situation i.e. the deletion of I-A genes. A detailed structural understanding of the similarities and differences between I-A and the paralogous I-E could help illuminate the respective roles these molecules play 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. 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 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 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.

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                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 204797     5 PTVSIFPPSSEQLATGGaSVVCFINNFYPKDISVKWkIDGSERQNDVLNSVTDQDSKDSTYSMSSTLTLTKADyesHNLF 84
Cdd:cd21006   3 PQATVFPKSPVLLGQPN-TLICFVDNIFPPVINITW-LRNSKSVTDGVYETSFLVNRDHSFHKLSYLTFIPSD---DDIY 77

                        90
                ....*....|....*...
gi 204797    85 VCEVVHKTSASPIVKSFN 102
Cdd:cd21006  78 DCKVEHWGLEEPVLKHWE 95

Class II major histocompatibility complex (MHC) beta chain immunoglobulin domain of histocompatibility antigen (HLA) DM; 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 histocompatibility antigen (HLA) DM. Human HLA-DM plays a critical role in antigen presentation to CD4 T cells by catalyzing the exchange of peptides bound to MHC class II molecules. Type 1 diabetes is correlated with DM activation and it is also implicated in viral infections such as herpes simplex virus, celiac disease, multiple sclerosis, other autoimmune diseases, and leukemia. 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 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 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.

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                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 204797     5 PTVSIFP------PSSEQLAtggasvvCFINNFYPKDISVKWKIDGSERQNDVLNSVTDQDSKDSTYSMSSTLTLTKady 78
Cdd:cd21002   4 PSVRVAPttpfntREPVMLA-------CHVWGFYPADVTITWLKNGDPVAPHSSAPKTAQPNGDWTYQTQVTLAVTP--- 73

                        90       100
                ....*....|....*....|.
gi 204797    79 ESHNLFVCEVVHKTSASPIVK 99
Cdd:cd21002  74 SPGDTYTCSVQHASLPEPLLE 94