Partial amino acid sequences of the heavy chains of human HLA histocompatibility antigens

Abstract

HLA antigens are composed of two polypeptide chains, the heavy chain carrying the alloantigenic determinants and the light chain identified as β 2-microglobulin. By the use of microsequencing techniques, the amino terminal sequences of two HLA heavy chain preparations carrying different HLA allospecificities (A2 and B7, 14) have been determined through position 22. With the exception of one position, the two are identical through 22 residues. There is also a considerable degree of homology with mouse H-2 antigens. These data support the hypothesis that the HLA-A and B gene products have evolved by gene duplication from a common ancestral gene and that these gene products have great homology in the primary structure.