HLA-A

HLA-A is a group of human leukocyte antigens (HLA) that are coded for by the HLA-A locus, which is located at human chromosome 6p21.3. HLA is a major histocompatibility complex (MHC) antigen specific to humans. HLA-A is one of three major types of human MHC class I cell surface receptors. The others are HLA-B and HLA-C. The receptor is a heterodimer, and is composed of a heavy α chain and smaller β chain. The α chain is encoded by a variant HLA-A gene, and the β chain (β2-microglobulin) is an invariant β2 microglobulin molecule. The β2 microglobulin protein is coded for by a separate region of the human genome.2XPG, 3RL1, 3RL2,%%s2BCK, 3I6L, 3NFN, 3QZW, 3VXM, 3VXN, 3VXO, 3VXP, 3VXR, 3VXS, 3VXU, 3W0W, 3WL9, 3WLB, 4F7M, 4F7P, 4F7T, 4WU5, 4WU7, 5HGA, 5HGD, 5HGB, 5HGH,%%s1Q94, 1QVO, 1X7Q, 2HN7, 4MJ5, 4MJ6, 4N8V, 4UQ2,%%s1W72, 3BO8, 4NQV, 4NQX, 5BRZ, 5BS0,%%s1AKJ, 1AO7, 1AQD, 1B0G, 1B0R, 1BD2, 1DUY, 1DUZ, 1EEY, 1EEZ, 1HHG, 1HHH, 1HHI, 1HHJ, 1HHK, 1HLA, 1I1F, 1I1Y, 1I4F, 1I7R, 1I7T, 1I7U, 1IM3, 1JF1, 1JHT, 1LP9, 1OGA, 1P7Q, 1QEW, 1QR1, 1QRN, 1QSE, 1QSF, 1S8D, 1S9W, 1S9X, 1S9Y, 1T1W, 1T1X, 1T1Y, 1T1Z, 1T20, 1T21, 1T22, 1TVB, 1TVH, 2AV1, 2AV7, 2BNQ, 2BNR, 2C7U, 2CLR, 2F53, 2F54, 2GIT, 2GJ6, 2GT9, 2GTW, 2GTZ, 2GUO, 2J8U, 2JCC, 2P5E, 2P5W, 2PYE, 2UWE, 2V2W, 2V2X, 2VLJ, 2VLK, 2VLL, 2VLR, 2X4N, 2X4O, 2X4P, 2X4Q, 2X4R, 2X4S, 2X4T, 2X4U, 2X70, 3BGM, 3BH8, 3BH9, 3BHB, 3D25, 3D39, 3D3V, 3FQN, 3FQR, 3FQT, 3FQU, 3FQW, 3FQX, 3FT2, 3FT3, 3FT4, 3GIV, 3GJF, 3GSN, 3GSO, 3GSQ, 3GSR, 3GSU, 3GSV, 3GSW, 3GSX, 3H7B, 3H9H, 3H9S, 3HAE, 3HLA, 3HPJ, 3I6G, 3I6K, 3IXA, 3KLA, 3MGO, 3MGT, 3MR9, 3MRB, 3MRC, 3MRD, 3MRF, 3MRG, 3MRH, 3MRI, 3MRJ, 3MRK, 3MRL, 3MRM, 3MRN, 3MRO, 3MRP, 3MRQ, 3MRR, 3MYJ, 3O3A, 3O3B, 3O3D, 3O3E, 3PWJ, 3PWL, 3PWN, 3PWP, 3QDG, 3QDJ, 3QDM, 3QEQ, 3QFD, 3QFJ, 3REW, 3TO2, 3UTQ, 3UTS, 3UTT, 3V5D, 3V5H, 3V5K, 4E5X, 4EMZ, 4EN2, 4EUP, 4FTV, 4GKN, 4GKS, 4I4W, 4JFD, 4JFE, 4JFF, 4JFO, 4JFP, 4JFQ, 4K7F, 4L29, 4L3C, 4L3E, 4MNQ, 4NNX, 4NNY, 4NO0, 4NO2, 4NO3, 4NO5, 4OV5, 4QOK, 4U6X, 4U6Y, 4UQ3, 4WJ5, 4WUU, 5EU3, 5EU5, 5EU4, 5D2L, 5D2N, 5EU6, 5HHQ, 5HHO, 5HHM, 5C09, 5C0F, 5E9D, 5C0G, 5C0A, 4ZEZ, 5C0I, 5D9S, 5HYJ, 5C0H, 5C0J, 5C0E, 5C0C, 5C0B, 5C07, 5C0D, 5C08, 5HHN,%%s1HSB, 1TMC, 2HLA, 4HWZ, 4HX1, 4I48310515013ENSG00000227715ENSG00000235657ENSG00000231834ENSMUSG00000091705P30455Q09160P01892P30450P18462P16189P16190P10314P30457P30453P30459P01891P30456P10316P30512P30447n/aNM_001242758NM_002116NM_010392NM_001368740NP_001229687NP_002107NP_001229687.1n/a1akj: COMPLEX OF THE HUMAN MHC CLASS I GLYCOPROTEIN HLA-A2 AND THE T CELL CORECEPTOR CD81ao7: COMPLEX BETWEEN HUMAN T-CELL RECEPTOR, VIRAL PEPTIDE (TAX), AND HLA-A 02011b0g: CLASS I HISTOCOMPATIBILITY ANTIGEN (HLA-A2.1)/BETA 2-MICROGLOBULIN/PEPTIDE P1049 COMPLEX1b0r: CRYSTAL STRUCTURE OF HLA-A*0201 COMPLEXED WITH A PEPTIDE WITH THE CARBOXYL-TERMINAL GROUP SUBSTITUTED BY A METHYL GROUP1bd2: COMPLEX BETWEEN HUMAN T-CELL RECEPTOR B7, VIRAL PEPTIDE (TAX) AND MHC CLASS I MOLECULE HLA-A 02011duy: CRYSTAL STRUCTURE OF HLA-A*0201/OCTAMERIC TAX PEPTIDE COMPLEX1duz: HUMAN CLASS I HISTOCOMPATIBILITY ANTIGEN (HLA-A 0201) IN COMPLEX WITH A NONAMERIC PEPTIDE FROM HTLV-1 TAX PROTEIN1eey: Crystal Structure Determination Of HLA A2 Complexed to Peptide GP2 with the substitution (I2L/V5L/L9V)1eez: Crystal Structure Determination of HLA-A2.1 Complexed to GP2 Peptide Variant(I2L/V5L)1hhg: THE ANTIGENIC IDENTITY OF PEPTIDE(SLASH)MHC COMPLEXES: A COMPARISON OF THE CONFORMATION OF FIVE PEPTIDES PRESENTED BY HLA-A21hhh: THE ANTIGENIC IDENTITY OF PEPTIDE(SLASH)MHC COMPLEXES: A COMPARISON OF THE CONFORMATION OF FIVE PEPTIDES PRESENTED BY HLA-A21hhi: THE ANTIGENIC IDENTITY OF PEPTIDE(SLASH)MHC COMPLEXES: A COMPARISON OF THE CONFORMATION OF FIVE PEPTIDES PRESENTED BY HLA-A21hhj: THE ANTIGENIC IDENTITY OF PEPTIDE(SLASH)MHC COMPLEXES: A COMPARISON OF THE CONFORMATION OF FIVE PEPTIDES PRESENTED BY HLA-A21hhk: THE ANTIGENIC IDENTITY OF PEPTIDE(SLASH)MHC COMPLEXES: A COMPARISON OF THE CONFORMATION OF FIVE PEPTIDES PRESENTED BY HLA-A21hsb: DIFFERENT LENGTH PEPTIDES BIND TO HLA-AW68 SIMILARLY AT THEIR ENDS BUT BULGE OUT IN THE MIDDLE1i1f: CRYSTAL STRUCTURE OF HUMAN CLASS I MHC (HLA-A2.1) COMPLEXED WITH BETA 2-MICROGLOBULIN AND HIV-RT VARIANT PEPTIDE I1Y1i1y: CRYSTAL STRUCTURE OF HUMAN CLASS I MHC (HLA-A2.1) COMPLEXED WITH BETA 2-MICROGLOBULIN AND HIV-RT VARIANT PEPTIDE I1Y1i4f: CRYSTAL STRUCTURE OF HLA-A*0201/MAGE-A4-PEPTIDE COMPLEX1i7r: CRYSTAL STRUCTURE OF CLASS I MHC A2 IN COMPLEX WITH PEPTIDE P10581i7t: CRYSTAL STRUCTURE OF CLASS I MHC A2 IN COMPLEX WITH PEPTIDE P1049-5V1i7u: CRYSTAL STRUCTURE OF CLASS I MHC A2 IN COMPLEX WITH PEPTIDE P1049-6V1im3: Crystal Structure of the human cytomegalovirus protein US2 bound to the MHC class I molecule HLA-A2/tax1jf1: Crystal structure of HLA-A2*0201 in complex with a decameric altered peptide ligand from the MART-1/Melan-A1jht: Crystal structure of HLA-A2*0201 in complex with a nonameric altered peptide ligand (ALGIGILTV) from the MART-1/Melan-A.1lp9: Xenoreactive complex AHIII 12.2 TCR bound to p1049/HLA-A2.11oga: A STRUCTURAL BASIS FOR IMMUNODOMINANT HUMAN T-CELL RECEPTOR RECOGNITION.1p7q: Crystal Structure of HLA-A2 Bound to LIR-1, a Host and Viral MHC Receptor1q94: Structures of HLA-A*1101 in complex with immunodominant nonamer and decamer HIV-1 epitopes clearly reveal the presence of a middle anchor residue1qew: HUMAN CLASS I HISTOCOMPATIBILITY ANTIGEN (HLA-A 0201) COMPLEX WITH A NONAMERIC PEPTIDE FROM MELANOMA-ASSOCIATED ANTIGEN 3 (RESIDUES 271-279)1qr1: POOR BINDING OF A HER-2/NEU EPITOPE (GP2) TO HLA-A2.1 IS DUE TO A LACK OF INTERACTIONS IN THE CENTER OF THE PEPTIDE1qrn: CRYSTAL STRUCTURE OF HUMAN A6 TCR COMPLEXED WITH HLA-A2 BOUND TO ALTERED HTLV-1 TAX PEPTIDE P6A1qse: STRUCTURE OF HUMAN A6-TCR BOUND TO HLA-A2 COMPLEXED WITH ALTERED HTLV-1 TAX PEPTIDE V7R1qsf: STRUCTURE OF A6-TCR BOUND TO HLA-A2 COMPLEXED WITH ALTERED HTLV-1 TAX PEPTIDE Y8A1qvo: STRUCTURES OF HLA-A*1101 IN COMPLEX WITH IMMUNODOMINANT NONAMER AND DECAMER HIV-1 EPITOPES CLEARLY REVEAL THE PRESENCE OF A MIDDLE ANCHOR RESIDUE1s8d: Structural basis for degenerate recognition of HIV peptide variants by cytotoxic lymphocyte, variant SL9-3A1s9w: Crystal Structure Analysis of NY-ESO-1 epitope, SLLMWITQC, in complex with HLA-A21s9x: Crystal Structure Analysis of NY-ESO-1 epitope analogue, SLLMWITQA, in complex with HLA-A21s9y: Crystal Structure Analysis of NY-ESO-1 epitope analogue, SLLMWITQS, in complex with HLA-A21t1w: Structural basis for degenerate recognition of HIV peptide variants by cytotoxic lymphocyte, variant SL9-3F6I8V1t1x: Structural basis for degenerate recognition of HIV peptide variants by cytotoxic lymphocyte, variant SL9-4L1t1y: Structural basis for degenerate recognition of HIV peptide variants by cytotoxic lymphocyte, variant SL9-5V1t1z: Structural basis for degenerate recognition of HIV peptide variants by cytotoxic lymphocyte, variant SL9-6A1t20: Structural basis for degenerate recognition of HIV peptide variants by cytotoxic lymphocyte, variant SL9-6I1t21: Structural basis for degenerate recognition of HIV peptide variants by cytotoxic lymphocyte, variant SL9, monoclinic crystal1t22: Structural basis for degenerate recognition of HIV peptide variants by cytotoxic lymphocyte, variant SL9, orthorhombic crystal1tmc: THE THREE-DIMENSIONAL STRUCTURE OF A CLASS I MAJOR HISTOCOMPATIBILITY COMPLEX MOLECULE MISSING THE ALPHA3 DOMAIN OF THE HEAVY CHAIN1tvb: Crystal structure of Melanoma Antigen gp100(209-217) Bound to Human Class I MHC HLA-A21tvh: Crystal structure of Modified Melanoma Antigen gp100(209-T2M) Bound to Human Class I MHC HLA-A21w72: CRYSTAL STRUCTURE OF HLA-A1:MAGE-A1 IN COMPLEX WITH FAB-HYB31x7q: Crystal structure of HLA-A*1101 with sars nucleocapsid peptide2av1: Crystal structure of HTLV-1 TAX peptide Bound to Human Class I MHC HLA-A2 with the E63Q and K66A mutations in the heavy chain.2av7: Crystal structure of HTLV-1 TAX peptide Bound to Human Class I MHC HLA-A2 with the K66A mutation in the heavy chain.2bck: Crystal Structure of HLA-A*2402 Complexed with a telomerase peptide2bnq: STRUCTURAL AND KINETIC BASIS FOR HEIGHTENED IMMUNOGENICITY OF T CELL VACCINES2bnr: STRUCTURAL AND KINETIC BASIS FOR HEIGHTENED IMMUNOGENICITY OF T CELL VACCINES2bsu:2bsv:2c7u: CONFLICTING SELECTIVE FORCES AFFECT CD8 T-CELL RECEPTOR CONTACT SITES IN AN HLA-A2 IMMUNODOMINANT HIV EPITOPE.2clr: THREE DIMENSIONAL STRUCTURE OF A PEPTIDE EXTENDING OUT ONE END OF A CLASS I MHC BINDING SITE2f53: Directed Evolution of Human T-cell Receptor CDR2 residues by phage display dramatically enhances affinity for cognate peptide-MHC without apparent cross-reactivity2f54: Directed evolution of human T cell receptor CDR2 residues by phage display dramatically enhances affinity for cognate peptide-MHC without increasing apparent cross-reactivity2git: Human Class I MHC HLA-A2 in complex with the modified HTLV-1 TAX (Y5K-4--butyric acid) peptide2gj6: The complex between TCR A6 and human Class I MHC HLA-A2 with the modified HTLV-1 TAX (Y5K-4--butyric acid) peptide2hla: SPECIFICITY POCKETS FOR THE SIDE CHAINS OF PEPTIDE ANTIGENS IN HLA-AW682hn7: HLA-A*1101 in complex with HBV peptide homologue3hla: HUMAN CLASS I HISTOCOMPATIBILITY ANTIGEN A2.1 HLA-A is a group of human leukocyte antigens (HLA) that are coded for by the HLA-A locus, which is located at human chromosome 6p21.3. HLA is a major histocompatibility complex (MHC) antigen specific to humans. HLA-A is one of three major types of human MHC class I cell surface receptors. The others are HLA-B and HLA-C. The receptor is a heterodimer, and is composed of a heavy α chain and smaller β chain. The α chain is encoded by a variant HLA-A gene, and the β chain (β2-microglobulin) is an invariant β2 microglobulin molecule. The β2 microglobulin protein is coded for by a separate region of the human genome. MHC Class I molecules such as HLA-A are part of a process that presents short polypeptides to the immune system. These polypeptides are typically 7-11 amino acids in length and originate from proteins being expressed by the cell. There are two classes of polypeptide that can be presented by an HLA protein: those that are supposed to be expressed by the cell (self) and those of foreign derivation (non-self). Under normal conditions cytotoxic T cells, which normally patrol the body in the blood, 'read' the peptide presented by the complex. T cells, if functioning properly, only bind to non-self peptides. If binding occurs, a series of events is initiated culminating in cell death via apoptosis. In this manner, the human body eliminates any cells infected by a virus or expressing proteins they shouldn't be (e.g. cancerous cells). For humans, as in most mammalian populations, MHC Class I molecules are extremely variable in their primary structure, and HLA-A is ranked among the genes in humans with the fastest-evolving coding sequence. As of December 2013, there are 2432 known HLA-A alleles coding for 1740 active proteins and 117 null proteins. This level of variation on MHC Class I is the primary cause of transplant rejection, as random transplantation between donor and host is unlikely to result in a matching of HLA-A, B or C antigens. Evolutionary biologists also believe that the wide variation in HLAs is a result of a balancing act between conflicting pathogenic pressures. Greater variety of HLAs decreases the probability that the entire population will be wiped out by a single pathogen as certain individuals will be highly resistant to each pathogen. The effect of HLA-A variation on HIV/AIDS progression is discussed below.