THE ROLE OF MELANOCYTE-STIMULATING HORMONE (MSH) RECEPTOR IN BOVINE COAT COLOR DETERMINATION

The melanocyte-stimulating hormone (MSH) receptor has a major function in the regulation of black (eumelanin) versus red (phaeomelanin) pigment synthesis within melanocytes. We report three alleles of the MSH-receptor gene found in cattle. A point mutation in the dominant allele E(D) gives black coat color, whereas a frameshift mutation, producing a prematurely terminated receptor, in homozygous e/e animals, produces red coat color. The wild-type allele E(+) produces a variety of colors, reflecting the possibilities for regulating the normal receptor. Microsatellite analysis, RFLP studies, and coat color information were used to localize the MSH-receptor to bovine Chromosome (Chr) 18.