IUBMB Enzyme Nomenclature


Accepted name: 3β-hydroxysteroid 3-dehydrogenase

Reaction: a 3β-hydroxysteroid + NADP+ = a 3-oxosteroid + NADPH + H+

For diagram of reaction, click here

Other name(s): 3-keto-steroid reductase; 3-KSR; HSD17B7 (gene name); ERG27 (gene name)

Systematic name: 3β-hydroxysteroid:NADP+ 3-oxidoreductase

Comments: The enzyme acts on multiple 3β-hydroxysteroids. Participates in the biosynthesis of zemosterol and cholesterol, where it catalyses the reaction in the opposite direction to that shown. The mammalian enzyme is bifunctional and also catalyses EC, 17β-estradiol 17-dehydrogenase [4].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 42616-29-5


1. Swindell, A.C. and Gaylor, J.L. Investigation of the component reactions of oxidative sterol demethylation. Formation and metabolism of 3-ketosteroid intermediates. J. Biol. Chem. 243 (1968) 5546-5555. [PMID: 4387005]

2. Billheimer, J.T., Alcorn, M. and Gaylor, J.L. Solubilization and partial purification of a microsomal 3-ketosteroid reductase of cholesterol biosynthesis. Purification and properties of 3β-hydroxysteroid dehydrogenase and Δ5-3-ketosteroid isomerase from bovine corpora lutea. Arch. Biochem. Biophys. 211 (1981) 430-438. [PMID: 6946726]

3. Gachotte, D., Sen, S.E., Eckstein, J., Barbuch, R., Krieger, M., Ray, B.D. and Bard, M. Characterization of the Saccharomyces cerevisiae ERG27 gene encoding the 3-keto reductase involved in C-4 sterol demethylation. Proc. Natl. Acad. Sci. USA 96 (1999) 12655-12660. [PMID: 10535978]

4. Marijanovic, Z., Laubner, D., Moller, G., Gege, C., Husen, B., Adamski, J. and Breitling, R. Closing the gap: identification of human 3-ketosteroid reductase, the last unknown enzyme of mammalian cholesterol biosynthesis. Mol. Endocrinol. 17 (2003) 1715-1725. [PMID: 12829805]

[EC created 2002, modified 2012]

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