HLA-B16 antigens: sequence of the ST-16 antigen, further definition of two B38 subtypes and evidence for convergent evolution of B*3902.

The ST-16 antigenic specificity of the HLA-B locus is defined as a B39 variant of Mexican-Americans. Nucleotide sequencing of cDNA shows the ST-16 allele (B3905) differs from B39011 by a single substitution that substitutes tyrosine for aspartic acid at position 74 of the mature class I heavy chain. The complete coding region sequence for the common caucasoid allele encoding the B38 antigen has been determined. This B3801 allele differs from B3802 at two nucleotide substitutions within the Bw4 sequence motif. B3801 and B3802 may have been derived independently from B39011 by conversion events with B alleles donating distinctive Bw4 motifs. A novel allele B39022 derived from a Colombian Indian differs from the B39021 allele of Japanese origin at two widely separated silent substitutions. Comparison of sequences for the known B16 alleles suggest that B39021 and B39022 were independently derived by recombination from B39013 and B*39011 respectively.