Tang P M, Chiang J Y
Biochem Biophys Res Commun. 1986 Jan 29;134(2):797-802. doi: 10.1016/s0006-291x(86)80491-0.
Cholesterol 7 alpha-hydroxylase activity was completely inhibited by incubation with alkaline phosphatase in a reconstituted enzyme system containing a cytochrome P-450, NADPH-cytochrome P-450 reductase and phospholipid. On the other hand, cAMP-dependent protein kinase stimulated cholesterol 7 alpha-hydroxylase activity by 2.5-fold. The modulation of cholesterol 7 alpha-hydroxylase activity was dependent on the amount of phosphatase or kinase added. The phosphatase inhibited enzyme activity was partially reversed by the treatment with protein kinase. These experiments indicate that the reconstituted cholesterol 7 alpha-hydroxylase activity is reversibly regulated by phosphorylation/dephosphorylation mechanism.
在含有细胞色素P-450、NADPH-细胞色素P-450还原酶和磷脂的重组酶系统中，胆固醇7α-羟化酶活性通过与碱性磷酸酶孵育而被完全抑制。另一方面，cAMP依赖性蛋白激酶使胆固醇7α-羟化酶活性增强了2.5倍。胆固醇7α-羟化酶活性的调节取决于所添加的磷酸酶或激酶的量。用蛋白激酶处理可部分逆转磷酸酶对酶活性的抑制作用。这些实验表明，重组的胆固醇7α-羟化酶活性通过磷酸化/去磷酸化机制受到可逆调节。
