MOLECULAR CHARACTERIZATION OF THE RH-LIKE LOCUS AND GENE TRANSCRIPTS FROM THE RHESUS-MONKEY (MACACA-MULATTA)

The human Rh blood group locus consists of two structurally related ge nes (D and CcEe) in Rh-positive haplotypes but a single gene (CcEe) in Rh-negative haplotypes. The genome of rhesus monkeys (Macaca mulatta) , while not expressing any of the human Rh D, C, c, E, or e specificit ies, carries a Rh-like locus strongly related to the human Rh locus. S outhern blot analysis suggested the presence of only one Rh-like gene with an additional truncated fragment corresponding to the 5' region. RNA preparations from M. mulatta bone marrow cells contained Rh-like s pecies of 1.7 kb. Two allelic Rh-like transcripts were amplified by PC R and sequenced. The predicted translation product of the first transc ript was a 417-amino-acid protein closely similar to the human Rh coun terpart. The predicted product of the second transcript consisted of a 361-amino-acid polypeptide truncated in the NH, terminal region and d iffering from the former by a few substitutions. The macaque Rh-like p rotein sequences differed from those of human D and Cc/Ee polypeptides by 22-25%, whereas the degree of identity between the human proteins was 91.5%. Implications of these results in the analysis of the evolut ionary pathway of the Rh locus are discussed.