The bm13 mutation consists of four nucleotide changes that result in amino acid changes in codons 114 (leucine to glycine), 116 (phenylalanine to tyrosine) and 119 (glutamate to aspartate). A mutation in codon 118 is silent. The mutation is thought to have arisen by a gene conversion event with the H-2Kb acting as the donor locus. (J:106337)