CYP11B1

A cytochrome P450 monooxygenase mainly involved in the biosynthesis of adrenal corticoids. Catalyzes a variety of reactions that are essential for many species, including detoxification, defense, and the formation of endogenous chemicals like steroid hormones. Steroid 11beta, 18- and 19-hydroxylase with preferred regioselectivity at 11beta, then 18, and lastly 19 (By similarity). Catalyzes the hydroxylation of 11-deoxycortisol and 11-deoxycorticosterone (21-hydroxyprogesterone) at 11beta position, yielding cortisol or corticosterone, respectively, but cannot produce aldosterone. Mechanistically, uses molecular oxygen inserting one oxygen atom into a substrate for hydroxylation 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). Due to its lack of 18-oxidation activity, it is incapable of generating aldosterone. Besides its role in the biosynthesis of mineralocorticoids and glucocorticoids, it can also participate in the androgen metabolic pathway, converting androst-4-ene-3,17-dione to 11beta-hydroxyandrost-4-ene-3,17-dione, and testosterone (17beta-hydroxy-4-androsten-3-one) to 11beta,17beta-dihydroxyandrost-4-ene-3-one..

Function from UniProtKB (P15538), read 2026-09-23. CC BY 4.0.