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Aldosterone synthase, also called steroid 18-hydroxylase, corticosterone 18-monooxygenase or P450C18, is a steroid hydroxylase cytochrome P450 enzyme involved in the biosynthesis of the mineralocorticoid aldosterone and other steroids. The enzyme catalyzes sequential hydroxylations of the steroid angular methyl group at C18 after initial 11β ...
It spontaneously and reversibly converts to various less polar forms and derivatives, some of which serve as precursors to aldosterone or corticosterone. Specifically, 21-hydroxy-11,18-oxido-4-pregnene-3,20-dione (18-DAL) is hydroxylated to aldosterone in the presence of malate and NADP+ at pH 4.8, indicating that 18-DAL acts as a metabolic ...
Corticosterone has only weak glucocorticoid and mineralocorticoid potencies in humans and is important mainly as an intermediate in the steroidogenic pathway from pregnenolone to aldosterone. Corticosterone is converted to aldosterone by aldosterone synthase , found only in the mitochondria of glomerulosa cells.
18-Hydroxylase (aldosterone synthase) – mineralocorticoid synthesis; 21-Hydroxylase – corticosteroid synthesis; Cytochrome P450 (CYP1, 2, 3) – estrogen metabolism; Hydroxysteroid dehydrogenases (and ketosteroid reductases) 3α-Hydroxysteroid dehydrogenase – androgen, progestogen, and neurosteroid synthesis and metabolism
The genes encoding aldosterone synthase and 11β-hydroxylase are 95% identical and are close together on chromosome 8. In individuals with GRA, there is unequal crossing over so that the 5' regulatory region of the 11-hydroxylase gene is fused to the coding region of the aldosterone synthase. [citation needed]
Aldosterone release causes sodium and water retention, which causes increased blood volume, and a subsequent increase in blood pressure, which is sensed by the baroreceptors. [39] To maintain normal homeostasis these receptors also detect low blood pressure or low blood volume, causing aldosterone to be released.
The outermost layer, the zona glomerulosa is the main site for the production of aldosterone, a mineralocorticoid. The synthesis and secretion of aldosterone are mainly regulated by the renin–angiotensin–aldosterone system. The zona glomerulosa cells express a specific enzyme aldosterone synthase (also known as CYP11B2).
This layer is the main site for production of aldosterone, a mineralocorticoid, by the action of the enzyme aldosterone synthase. [16] [17] Aldosterone plays an important role in the long-term regulation of blood pressure. [18]