Cytochrome P450 11β-hydroxylase (CYP11B1)

Cytochrome P450 11β-hydroxylase is a mitochondrial enzyme encoded by the CYP11B1 gene. It catalyzes the hydroxylation at the carbon position 11β on steroid precursors—primarily converting 11-deoxycortisol into cortisol and deoxycorticosterone into corticosterone, which are essential steps in glucocorticoid biosynthesis. The enzyme is highly expressed in the zona fasciculata of the adrenal cortex. Its activity is regulated by adrenocorticotropic hormone (ACTH). Mutations or deficiencies lead to congenital adrenal hyperplasia with symptoms ranging from virilization to hypertension depending on mutation severity. While it shares homology with aldosterone synthase (CYP11B2), it does not produce aldosterone itself. Pharmacological inhibition—such as by metyrapone—is clinically relevant for diagnostic testing but carries risks related to impaired stress response due to reduced cortisol synthesis.

Other names

Steroid 11β-hydroxylase11β-hydroxylaseC11B1 (gene/protein symbol)H11b (in some species and literature)

Inhibition of CYP11B1 blocks conversion of 11-deoxycortisol to cortisol, reducing glucocorticoid synthesis and increasing precursor steroids; this is exploited diagnostically or potentially therapeutically in conditions like Cushing’s syndrome or CAH management