IUBMB Enzyme Nomenclature


Accepted name: 24-hydroxycholesterol 7α-hydroxylase

Reaction: (24S)-cholest-5-ene-3β,24-diol + [reduced NADPH—hemoprotein reductase] + O2 = (24S)-cholest-5-ene-3β,7α,24-triol + [oxidized NADPH—hemoprotein reductase] + H2O

For diagram of reaction click here.

Glossary: (24S)-cholest-5-ene-3β,24-diol = (24S)-24-hydroxycholesterol

Other name(s): 24-hydroxycholesterol 7α-monooxygenase; CYP39A1; CYP39A1 oxysterol 7α-hydroxylase

Systematic name: (24S)-cholest-5-ene-3β,24-diol,NADPH—hemoprotein reductase:oxygen oxidoreductase (7α-hydroxylating)

Comments: A P450 heme-thiolate protein that is found in liver microsomes and in ciliary non-pigmented epithelium [2]. The enzyme is specific for (24S)-cholest-5-ene-3β,24-diol, which is formed mostly in the brain by EC, cholesterol 24-hydroxylase. The direct electron donor to the enzyme is EC, NADPH—hemoprotein reductase.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number:


1. Li-Hawkins, J., Lund, E.G., Bronson, A.D. and Russell, D.W. Expression cloning of an oxysterol 7α-hydroxylase selective for 24-hydroxycholesterol. J. Biol. Chem. 275 (2000) 16543-16549. [PMID: 10748047]

2. Ikeda, H., Ueda, M., Ikeda, M., Kobayashi, H. and Honda, Y. Oxysterol 7alpha-hydroxylase (CYP39A1) in the ciliary nonpigmented epithelium of bovine eye. Lab. Invest. 83 (2003) 349-355. [PMID: 12649335]

3. Russell, D.W. The enzymes, regulation, and genetics of bile acid synthesis. Annu. Rev. Biochem. 72 (2003) 137-174. [PMID: 12543708]

[EC created 2005 as EC, transferred 2016 to EC]

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