title: Primary structure of papain-solubilized human histocompatibility antigen HLA-B40 (-Bw60). An outline of alloantigenic determinants.
abstract: The primary structure of papain-solubilized human histocompatibility antigen HLA-B40 (-Bw60) has been determined. Its comparison with that of the cross-reactive HLA-B7 antigen allows for the first time a direct sequence comparison between two HLA-B locus products and an outline of the location of their alloantigenic sites. Overall sequence homology between HLA-B40 and HLA-B7 is 93%. Of 19 detected differences, 18 are located in the two amino-terminal domains (residues 1-182). Half of them are clustered in two short segments spanning residues 63-74 and 147-156, respectively, which suggests that they may encompass major sites of their alloantigenic determinants. The first of these segments is highly polymorphic in HLA and H-2 molecules. It is proposed that it may belong to a hypervariable region of class I histocompatibility antigens. The remaining substitutions are scattered through the N-terminal portions of the two external domains. Thus, in addition to the above-mentioned segments, other positions may contribute significantly to the antigenic polymorphism of these molecules.
mesh_terms: D000595:Amino Acid Sequence; D002918:Chymotrypsin; D003488:Cyanogen Bromide; D000939:Epitopes / Q000032:analysis*; D006680:HLA Antigens / Q000302:isolation & purification*; D015235:HLA-B Antigens; D059947:HLA-B40 Antigen; D015793:HLA-B7 Antigen; D006801:Humans; D007519:Isoantigens / Q000032:analysis*; D046911:Macromolecular Substances; D010206:Papain; D010446:Peptide Fragments / Q000032:analysis
chemical_list: D000939:Epitopes; D006680:HLA Antigens; D015235:HLA-B Antigens; D059947:HLA-B40 Antigen; D015793:HLA-B7 Antigen; D007519:Isoantigens; D046911:Macromolecular Substances; D010446:Peptide Fragments; D002918:Chymotrypsin; D010206:Papain; D003488:Cyanogen Bromide