This gene encodes a minor histocompatibility antigen that is involved in tissue graft rejection and is polymorphic in different mouse strains. The 5' region of this gene, including the translational start codon and the first 293 amino acids, is absent from the C57BL/6J genome. The encoded antigen is not thought to be expressed in C57BL/6J. [provided by RefSeq, Mar 2013]