HUMAN H-Y - A MALE-SPECIFIC HISTOCOMPATIBILITY ANTIGEN DERIVED FROM THE SMCY PROTEIN

H-Y is a transplantation antigen that can lead to rejection of male or gan and bone marrow grafts by female recipients, even if the donor and recipient match at the major histocompatibility locus of humans, the HLA (human leukocyte antigen) locus, However, the origin and function of H-Y antigens has eluded researchers for 40 years. One human H-Y ant igen presented by HLA-B7 was identified as an 11-residue peptide deriv ed from SMCY, an evolutionarily conserved protein encoded on the Y chr omosome, The protein from the homologous gene on the X chromosome, SMC X, differs by two amino acid residues in the same region. The identifi cation of H-Y may aid in transplantation prognosis, prenatal diagnosis , and fertilization strategies.