A single amino acid change makes the peptide specificity of B*3910 unrelated to B*3901 and closer to a group of HLA-B proteins including the malaria-protecting allotype HLA-B53

HLA-B*3910, which has only been found in African and African American indiv iduals, differs hom B*3901 by the single amino acid change of Cys67 to Tyr6 7. Sequence analysis of the B*3910-bound peptide pool and of several indivi dual ligands revealed that this subtype has strong preference for peptides with Pro2. This is in contrast with the preference of B*3901 for peptides w ith basic residues (Arg and His) at this position, and indicates that the s ingle amino acid substitution between B*3910 and B*3901 totally changes the repertoire of bound peptides. This is presumably due to the significant de crease in the size of the B pocket, and to its increased hydrophobicity, si nce Tyr67 takes part in this pocket. B*3910 is similar to various other cla ss I proteins in its preference for peptides with Pro2 and nonpolar C-termi nal residues, including HLA-B53, an antigen associated with protection agai nst severe malaria. The role of these two motifs as major peptidic anchors suggests that B*3910 and HLA-B53 may bind common peptides.