Localization of cytochrome P-450-linked mixed function oxidase and steroid hydroxylations within zones of bovine adrenocortices.

The localization of contents and activities of components of cytochrome P-450-linked mixed function oxidase system and the hydroxylation of steroids in mitochondria and microsomes within zones of adrenocortices was investigated. NADPH-adrenodoxin reductase activity was higher in the zona glomerulosa than in the other zones. Adrenodoxin content was present at high concentration in the zona fasciculata. The localization of cytochrome P-450 within zones of adrenocortices has already been reported (Ichikawa, Y., Kuroda, M. and Yamano, T. (1970) J. Cell Biol 45, 640--653). The zona fasciculata contained more mitochondrial and microsomal cytochromes P-450 than the zona glomerulosa or zona reticularis. Cleavage activity of the side chain of cholesterol was found in three zones. However, particularly high activity was observed in the zona fasciculata and zona reticularis. 11beta-Hydroxylation was found in the zona glomerulosa. 21-Hydroxylation activity was especially higher in the zona fasciculata than in the other zones.