3beta-Hydroxysteroid dehydrogenase
（重定向自Progesterone reductase）
3β-Hydroxysteroid dehydrogenase/Δ isomerase (3β-HSD) (EC1.1.1.145) is an enzyme that catalyzes the biosynthesis of progesterone from pregnenolone, 17α-hydroxyprogesterone from 17α-hydroxypregnenolone, and androstenedione from dehydroepiandrosterone (DHEA) in the adrenal gland. It is the only enzyme in the adrenal pathway of corticosteroid synthesis that is not a member of the cytochrome P450 family. In humans, there are two 3β-HSD isozymes encoded by the HSD3B1 and HSD3B2 genes.