title: Sequence of the COOH-terminal hydrophilic region of histocompatibility antigens HLA-A2 and HLA-B7.
abstract: Detergent-solubilized HLA antigens were isolated from a human lymphoblastoid cell using an anti-beta2-microglobulin immunoaffinity column. The HLA-A and HLA-B locus products were separated by thin layer isoelectric focusing. Cleavage of the p44 chain of HLA-A2 and -B7 antigens with cyanogen bromide led to the isolation of a 31-amino-acid fragment from each. The fragments were sequenced and shown to be from the COOH-terminal end of the intact chains using carboxypeptidase Y. The fragment from the HLA-B7 chain, 55% of whose amino acids were polar, contained the 2 cysteine residues not found in the papain-derived molecule. The tentative sequence of the fragment from the HLA-A2 chain was similar to that of the HLA-B7 fragment but appeared not to contain any cysteine residues. The hydrophilic COOH-terminal region of HLA antigens, which directly follows the hydrophobic, membrane-binding segment, began with a cluster of basic amino acids. This arrangement of amino acids resembles that found at the COOH terminus of the red blood cell membrane protein, glycophorin.
mesh_terms: D000595:Amino Acid Sequence; D002460:Cell Line; D006680:HLA Antigens; D010446:Peptide Fragments / Q000032:analysis; D013501:Surface-Active Agents
chemical_list: D006680:HLA Antigens; D010446:Peptide Fragments; D013501:Surface-Active Agents