Cytochrome P450 11B2, mitochondrial
Function
A cytochrome P450 monooxygenase that catalyzes the biosynthesis of aldosterone, the main mineralocorticoid in the human body responsible for salt and water homeostasis, thus involved in blood pressure regulation, arterial hypertension, and the development of heart failure (PubMed:11856349, PubMed:12530636, PubMed:1518866, PubMed:15356073, PubMed:1594605, PubMed:1775135, PubMed:22446688, PubMed:23322723, PubMed:9814482, PubMed:9814506). Catalyzes three sequential oxidative reactions of 11-deoxycorticosterone (21-hydroxyprogesterone), namely 11-beta hydroxylation, followed by two successive oxidations at C18 yielding 18-hydroxy and then 18-oxo intermediates (that would not leave the enzyme active site during the consecutive hydroxylation reactions), ending with the formation of aldosterone (PubMed:11856349, PubMed:12530636, PubMed:1518866, PubMed:1594605, PubMed:1775135, PubMed:22446688, PubMed:23322723, PubMed:9814506). Can also produce 18-hydroxycortisol and 18-oxocortisol, derived from successive oxidations of cortisol at C18, normally found at very low levels, but significantly increased in primary aldosteronism, the most common form of secondary hypertension (PubMed:15356073, PubMed:9814482). Mechanistically, uses molecular oxygen inserting one oxygen atom into a substrate and reducing the second into a water molecule. Two electrons are provided by NADPH via a two-protein mitochondrial transfer system comprising flavoprotein FDXR (adrenodoxin/ferredoxin reductase) and nonheme iron-sulfur protein FDX1 or FDX2 (adrenodoxin/ferredoxin) (PubMed:11856349, PubMed:1594605, PubMed:23322723, PubMed:9814506). Could also be involved in the androgen metabolic pathway (Probable).
Involvement in disease
Corticosterone methyloxidase 1 deficiency
CMO-1 deficiency
Autosomal recessive disorder of aldosterone biosynthesis. There are two biochemically different forms of selective aldosterone deficiency be termed corticosterone methyloxidase (CMO) deficiency type 1 and type 2. In CMO-1 deficiency, aldosterone is undetectable in plasma, while its immediate precursor, 18-hydroxycorticosterone, is low or normal.
None
The disease is caused by variants affecting the gene represented in this entry.
Corticosterone methyloxidase 2 deficiency
CMO-2 deficiency
Autosomal recessive disorder of aldosterone biosynthesis. In CMO-2 deficiency, aldosterone can be low or normal, but at the expense of increased secretion of 18-hydroxycorticosterone. Consequently, patients have a greatly increased ratio of 18-hydroxycorticosterone to aldosterone and a low ratio of corticosterone to 18-hydroxycorticosterone in serum.
None
The disease is caused by variants affecting the gene represented in this entry.
Pathway
Steroid biosynthesis.
Sequence Similarities
Belongs to the cytochrome P450 family.
Tissue Specificity
Expressed sporadically in the zona glomerulosa (zG) of the adrenal cortex (conventional zonation), as well as in aldosterone-producing cell clusters (APCCs) composed of morphological zG cells in contact with the capsule (variegated zonation).
Cellular localization
- Mitochondrion inner membrane
- Peripheral membrane protein
Alternative names
Aldosterone synthase, Aldosterone-synthesizing enzyme, CYPXIB2, Cytochrome P-450Aldo, Cytochrome P-450C18, Steroid 18-hydroxylase, ALDOS, CYP11B2