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Aldosterone synthase is a protein which is only expressed in the zona glomerulosa [5] of the adrenal cortex and is primarily regulated by the renin–angiotensin system. [6] It is the sole enzyme capable of synthesizing aldosterone in humans and plays an important role in electrolyte balance and blood pressure. [7]
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]
The enzyme aldosterone synthase (also known as CYP11B2) acts in this location [3] [4] The expression of neuron-specific proteins in the zona glomerulosa cells of human adrenocortical tissues has been predicted and reported by several authors [5] [6] [7] and it was suggested that the expression of proteins like the neuronal cell adhesion ...
These enzymes are nearly identical (they share 11β-hydroxylation and 18-hydroxylation functions), but aldosterone synthase is also able to perform an 18-oxidation. Moreover, aldosterone synthase is found within the zona glomerulosa at the outer edge of the adrenal cortex; 11β-hydroxylase is found in the zona glomerulosa and zona fasciculata.
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).
It may be increased in 17α-hydroxylase deficiency, [4] in aldosterone synthase deficiency, [5] in primary aldosteronism, and may also indicate a histologic variant of the aldosteronoma. [4] Excessive secretion of 18-OH-DOC can cause mineralocorticoid excess syndrome, although these cases are very rare.
There is ongoing research on how Genetic variants in the CYP21A2 gene may lead to pathogenic conditions. A variant of this gene has been reported to cause autosomal dominant posterior polar cataract, suggesting that steroid 21-hydroxylase may be involved in the extra-adrenal biosynthesis of aldosterone and cortisol in the lens of the eye. [72]