Decreased dopachrome oxidoreductase activity in yellow mice.
Dopachrome oxidoreductase (DCOR) is a newly characterized enzyme in the melanin synthetic pathway, active in the conversion of dopachrome to 5,6-dihydroxyindole. DCOR and tyrosinase activity were measured in skin anagen hairbulbs from lethal yellow (Ay/a), sienna yellow (Asy/a) and recessive yellow (e/e) mice with and without treatment with melanocyte-stimulating hormone (MSH). DCOR activity was low (Asy/a) or absent (Ay/a, e/e) in yellow mice without MSH treatment, and increased dramatically in the lethal and sienna yellow mice with MSH. There was no increase in DCOR activity in recessive yellow mice with MSH. Corresponding tyrosinase activity was reduced in lethal yellow and sienna yellow mice without MSH, and increased with MSH. Tyrosinase activity was normal in recessive yellow mice without MSH and did not change with MSH. We conclude that DCOR is an MSH-sensitive enzyme and that DCOR activity is absent in recessive yellow melanocytes. The latter finding suggests that the extension locus may be the DCOR locus.
D000818:Animals; D004156:Catechol Oxidase / Q000172:deficiency / Q000235:genetics*; D019746:Intramolecular Oxidoreductases; D009074:Melanocyte-Stimulating Hormones / Q000494:pharmacology; D008544:Melanocytes / Q000201:enzymology; D051379:Mice; D008810:Mice, Inbred C57BL; D014442:Monophenol Monooxygenase / Q000378:metabolism; D009154:Mutation; D010859:Pigmentation Disorders / Q000201:enzymology* / Q000235:genetics
D009074:Melanocyte-Stimulating Hormones; D004156:Catechol Oxidase; D014442:Monophenol Monooxygenase; D019746:Intramolecular Oxidoreductases; C042501:dopachrome isomerase