EC - Steroid 21-monooxygenase

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IntEnz Enzyme Nomenclature


Accepted name:
steroid 21-monooxygenase
Other names:
steroid 21-hydroxylase
cytochrome p450 XXIA1
Systematic name:
steroid,NADPH—hemoprotein reductase:oxygen oxidoreductase (21-hydroxylating)




A P-450 heme-thiolate protein responsible for the conversion of progesterone and 17α-hydroxyprogesterone to their respective 21-hydroxylated derivatives, 11-deoxycorticosterone and 11-deoxycortisol. Involved in the biosynthesis of the hormones aldosterone and cortisol. The electron donor is EC, NADPH—hemoprotein reductase.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Protein domains and families: PROSITE:PDOC00081
Structural data: CSA , EC2PDB
Gene Ontology: GO:0004509
CAS Registry Number: 9029-68-9
UniProtKB/Swiss-Prot: (10) [show] [UniProt]


  1. Hayano, M. and Dorfman, R.I.
    The action of adrenal homogenates on progesterone, 17-hydroxyprogesterone and 21-desoxycortisone.
    Arch. Biochem. Biophys. 36 : 237-239 (1952). [PMID: 14934270]
  2. Plager, J.E. and Samuels, L.T.
    Synthesis of C14-17-hydroxy-11-desoxycorticosterone and 17-hydroxycorticosterone by fractionated extracts of adrenal homogenates.
    Arch. Biochem. Biophys. 42 : 477-478 (1953). [PMID: 13031650]
  3. Ryan, K.J. and Engel, L.L.
    Hydroxylation of steroids at carbon 21.
    J. Biol. Chem. 225 : 103-114 (1957). [PMID: 13416221]
  4. Kominami, S., Ochi, H., Kobayashi, Y., Takemori, S.
    Studies on the steroid hydroxylation system in adrenal cortex microsomes. Purification and characterization of cytochrome P-450 specific for steroid C-21 hydroxylation.
    J. Biol. Chem. 255 : 3386-3394 (1980). [PMID: 6767716]
  5. Martineau, I., Belanger, A., Tchernof, A., Tremblay, Y.
    Molecular cloning and expression of guinea pig cytochrome P450c21 cDNA (steroid 21-hydroxylase) isolated from the adrenals.
    J. Steroid Biochem. Mol. Biol. 86 : 123-132 (2003). [PMID: 14568563]
  6. Arase, M., Waterman, M. R., Kagawa, N.
    Purification and characterization of bovine steroid 21-hydroxylase (P450c21) efficiently expressed in Escherichia coli.
    Biochem. Biophys. Res. Commun. 344 : 400-405 (2006). [PMID: 16597434]

[EC created 1961 as EC, transferred 1965 to EC, transferred 1972 to EC, modified 2013]