HSD3B1

Function

A bifunctional enzyme responsible for the oxidation and isomerization of 3beta-hydroxy-Delta(5)-steroid precursors to 3-oxo-Delta(4)-steroids, an essential step in steroid hormone biosynthesis. Specifically catalyzes the conversion of pregnenolone to progesterone, 17alpha-hydroxypregnenolone to 17alpha-hydroxyprogesterone, dehydroepiandrosterone (DHEA) to 4-androstenedione, and androstenediol to testosterone. Additionally, catalyzes the interconversion between 3beta-hydroxy and 3-oxo-5alpha-androstane steroids controlling the bioavalability of the active forms. Specifically converts dihydrotestosterone to its inactive form 5alpha-androstanediol, that does not bind androgen receptor/AR. Also converts androstanedione, a precursor of testosterone and estrone, to epiandrosterone (PubMed:1401999, PubMed:2139411). Expected to use NAD(+) as preferred electron donor for the 3beta-hydroxy-steroid dehydrogenase activity and NADPH for the 3-ketosteroid reductase activity (Probable).

Pathway

Steroid hormone biosynthesis.

Steroid metabolism.

Sequence Similarities

Belongs to the 3-beta-HSD family.

Tissue Specificity

Placenta and skin (PubMed:1401999). Predominantly expressed in mammary gland tissue.

Cellular localization

• Endoplasmic reticulum membrane
• Single-pass membrane protein
• Mitochondrion membrane
• Single-pass membrane protein

Alternative names

3BH, HSDB3A, HSD3B1, 3 beta-hydroxysteroid dehydrogenase/Delta 5-->4-isomerase type 1, 3 beta-hydroxysteroid dehydrogenase/Delta 5-->4-isomerase type I, 3-beta-hydroxy-5-ene steroid dehydrogenase, 3-beta-hydroxy-Delta(5)-steroid dehydrogenase, 3-beta-hydroxysteroid 3-dehydrogenase, Delta-5-3-ketosteroid isomerase, Dihydrotestosterone oxidoreductase, Steroid Delta-isomerase, Trophoblast antigen FDO161G, 3-beta-HSD I

Database links

swissprot:P14060 omim:201810 swissprot:P26439 entrezGene:3283 entrezGene:3284 omim:109715