Aldosterone biosynthesis in mitochondria of isolated zones of adrenal cortex.
An assumption that the aldosterone-synthesizing enzyme exists only in zona glomerulosa cells apparently contradicts our recent findings that a purified bovine adrenocortical cytochrome P-45011 beta catalyzes the aldosterone formation and the enzyme exists in both zones of the adrenal cortex. To gain more insight into the zone specificity of aldosterone production, the aldosterone-synthesizing activity of mitochondria prepared from the isolated zones of adrenal cortex of various animal species was investigated. The intact mitochondria from the bovine or porcine zonae fasciculata-reticularis could not produce aldosterone whereas those from the zona glomerulosa produced it at a significant rate. When the mitochondria from the zonae fasciculata-reticularis were solubilized by the addition of cholate, they produced aldosterone from corticosterone at a rate comparable to that of those from the zona glomerulosa. The presence of specific factor(s) in the zonae fasciculata-reticularis mitochondria inhibiting expression of the aldosterone synthetic activity is discussed. The mitochondria of the rat zonae fasciculata-reticularis could hardly catalyze aldosterone synthesis under the detergent-solubilized conditions, whereas those of the zona glomerulosa could. Immunoblot analysis revealed that the mitochondria of the zonae fasciculata-reticularis contained a protein of Mr 51,000 which was immunocrossreactive with a monoclonal antibody directed against P-45011 beta, whereas those of the zona glomerulosa contained two immunocrossreactive proteins of Mr 51,000 and 49,000. These results suggest that in the case of rat adrenal cortex, a specific aldosterone-synthesizing enzyme exists in the zona glomerulosa.
Ohnishi
T
T
Department of Biochemistry, Osaka University Medical School, Japan.
Wada
A
A
Lauber
M
M
Yamano
T
T
Okamoto
M
M
D015069:18-Hydroxycorticosterone / Q000378:metabolism; D000302:Adrenal Cortex / Q000378:metabolism / Q000648:ultrastructure*; D000325:Adrenodoxin / Q000494:pharmacology; D000450:Aldosterone / Q000096:biosynthesis*; D000818:Animals; D002417:Cattle; D003345:Corticosterone / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D008928:Mitochondria / Q000378:metabolism*; D013552:Swine
D000325:Adrenodoxin; D000450:Aldosterone; D015069:18-Hydroxycorticosterone; D003345:Corticosterone