COMPARISON OF AMINO-ACID SEQUENCES OF 2 HUMAN HISTOCOMPATIBILITY ANTIGENS, HLA-A2 AND HLA-B7 - LOCATION OF PUTATIVE ALLOANTIGENIC SITES

The complete amino acid sequence for papain-solubilized HLA-B7 heavy chain is compared with the partial sequences of HLA-A2 and H-2K(b) heavy chains. Although these molecules are highly conserved (i.e., 80% homology in comparing HLA-B7 with HLA-A2; 72% and 74% homology in comparing H-2K(b) with HLA-A2 and HLA-B7, respectively), two stretches of greater variability are observed. These clusters of variability are discussed in terms of their possible involvement in the alloantigenic determinant(s) characteristic of these highly polymorphic membrane antigens.