Tamate H B, Hirobe T, Wakamatsu K, Ito S, Shibahara S, Ishikawa K
Department of Biochemistry, Yamagata University School of Medicine, Japan.
J Exp Zool. 1989 Jun;250(3):304-11. doi: 10.1002/jez.1402500310.
The levels of tyrosinase activities, tyrosinase cross-reacting material (TY-CRM), and tyrosinase mRNA were determined for skins from five congenic strains of mice (Mus musculus) with different coat colors. The dopa oxidase activity and melanin formation activity were directly proportional to the abundance of TY-CRM in all of the mutants. The levels of the enzyme activities and TY-CRM were increased in brown (b/b) and dilute (d/d) mice, while they were reduced in agouti (A/A) and pink-eyed dilution (p/p) animals. In albino (c/c) mice, the tyrosinase activities and melanin formation activity were scarcely detectable, and no TY-CRM was observed. Contrary to these, the levels of tyrosinase mRNA in agouti and albino mutants were almost the same as that in black mice, and those in brown and dilution mutants were 20-30% higher than that in black mice. These results indicate that the mutations at the brown and dilute loci exert their influence on the tyrosinase mRNA level, presumably by affecting the transcription of the tyrosinase gene, and that the mutations at the agouti and albino loci exert their influence on the TY-CRM level by regulating translation of tyrosinase mRNA and/or post-translation modification of the enzyme.
测定了具有不同毛色的五种近交系小鼠（小家鼠）皮肤中的酪氨酸酶活性、酪氨酸酶交叉反应物质（TY-CRM）和酪氨酸酶mRNA水平。在所有突变体中，多巴氧化酶活性和黑色素形成活性与TY-CRM的丰度直接成正比。棕色（b/b）和稀释（d/d）小鼠的酶活性和TY-CRM水平升高，而刺鼠（A/A）和粉红眼稀释（p/p）动物的酶活性和TY-CRM水平降低。在白化（c/c）小鼠中，几乎检测不到酪氨酸酶活性和黑色素形成活性，也未观察到TY-CRM。与此相反，刺鼠和白化突变体中的酪氨酸酶mRNA水平与黑色小鼠中的几乎相同，而棕色和稀释突变体中的酪氨酸酶mRNA水平比黑色小鼠中的高20%-30%。这些结果表明，棕色和稀释位点的突变可能通过影响酪氨酸酶基因的转录对酪氨酸酶mRNA水平产生影响，而刺鼠和白化位点的突变则通过调节酪氨酸酶mRNA的翻译和/或酶的翻译后修饰对TY-CRM水平产生影响。
