An H–YDb epitope is encoded by a novel mouse Y chromosome gene

Rejection of male tissue grafts by genotypically identical female mice has been explained by the existence of a male-specific transplantation antigen, H-Y (ref. 1), but the molecular nature of H-Y antigen has remained obscure. Hya, the murine locus controlling H-Y expression, has been localized to ΔSxrb, a deletion interval of the short arm of the Y chromosome2. In mice, H−Y antigen comprises at least four distinct epitopes, each recognized by a specific T lymphocyte clone..