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Available structures
PDB Ortholog search: PDBe RCSB
Aliases CYP17A1, CPT7, CYP17, P450C17, S17AH, cytochrome P450 family 17 subfamily A member 1
External IDs OMIM: 609300 MGI: 88586 HomoloGene: 73875 GeneCards: 1586
RNA expression pattern
PBB GE CYP17A1 205502 at tn.png
More reference expression data
Species Human Mouse
RefSeq (mRNA)



RefSeq (protein)



Location (UCSC) Chr 10: 102.83 – 102.84 Mb Chr 19: 46.67 – 46.67 Mb
PubMed search [1] [2]
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Cytochrome P450 17A1, also called steroid 17-alpha-monooxygenase, 17α-hydroxylase, 17,20 lyase, or 17,20 desmolase, is an enzyme of the hydroxylase type that in humans is encoded by the CYP17A1 gene. It is found in the zona reticularis of the adrenal cortex and zona fasciculata as well as gonadal tissues. This gene encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are generally regarded as monooxygenases that catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids, and other lipids, including the remarkable carbon-carbon bond scission catalyzed by this enzyme. This protein localizes to the endoplasmic reticulum. It has both 17alpha-hydroxylase and 17,20-lyase activities, and is a key enzyme in the steroidogenic pathway that produces progestins, mineralocorticoids, glucocorticoids, androgens, and estrogens.

More specifically, CYP17A1 acts upon pregnenolone and progesterone to add a hydroxyl (-OH) group at carbon 17 of the steroid D ring (the hydroxylase activity), or acts upon 17-hydroxyprogesterone and 17-hydroxypregnenolone to split the side-chain off the steroid nucleus (the lyase activity).[1]

Clinical significance[edit]

Mutations in this gene are associated with rare forms of congenital adrenal hyperplasia, specifically 17 alpha-hydroxylase deficiency/17,20-lyase deficiency and isolated 17,20-lyase deficiency.[2]

As a drug target[edit]

CYP17 inhibitors[edit]

The drug abiraterone, which is used to treat castration-resistant prostate cancer, blocks the biosynthesis of androgens by inhibiting the CYP17A1 enzyme. Abiraterone binds in the active site of the enzyme and coordinates the heme iron through its pyridine nitrogen, mimicking the subtrate.[3]

Since 2014, galeterone has been in phase III clinical trials for castration-resistant prostate cancer.[4]


17α-hydroxylase converts pregnenolone and progesterone to their 17-hydroxy forms, and converts 17-hydroxypregnenolone and 17-hydroxyprogesterone to DHEA and androstenedione, respectively. It corresponds to the downward arrows in this reaction scheme.
Steroidogenesis, showing, at left side, both reactions of 17-alpha hydroxylase, and both actions of 17, 20 lyase.

Additional images[edit]

See also[edit]


  1. ^ Boulpaep EL; Boron, WF (2005). Medical physiology: a cellular and molecular approach. St. Louis, Mo: Elsevier Saunders. p. 1180. ISBN 1-4160-2328-3. 
  2. ^ "Entrez Gene: CYP17A1 cytochrome P450, family 17, subfamily A, polypeptide 1". 
  3. ^ PDB: 3ruk​; DeVore NM, Scott EE (Feb 2012). "Structures of cytochrome P450 17A1 with prostate cancer drugs abiraterone and TOK-001". Nature 482 (7383): 116–9. doi:10.1038/nature10743. PMC 3271139. PMID 22266943. 
  4. ^ "Tokai Pharmaceuticals' Reformulated Galeterone Demonstrates Robust PSA Reductions in Advanced Prostate Cancer Patients" (Press release). Tokai Pharmaceuticals. January 29, 2014. 

Further reading[edit]

  • Miura K, Yasuda K, Yanase T, Yamakita N, Sasano H, Nawata H, Inoue M, Fukaya T, Shizuta Y (October 1996). "Mutation of cytochrome P-45017 alpha gene (CYP17) in a Japanese patient previously reported as having glucocorticoid-responsive hyperaldosteronism: with a review of Japanese patients with mutations of CYP17". The Journal of Clinical Endocrinology and Metabolism 81 (10): 3797–801. doi:10.1210/jcem.81.10.8855840. PMID 8855840. 
  • Miller WL, Geller DH, Auchus RJ (1999). "The molecular basis of isolated 17,20 lyase deficiency". Endocrine Research 24 (3-4): 817–25. doi:10.3109/07435809809032692. PMID 9888582. 
  • Strauss JF (November 2003). "Some new thoughts on the pathophysiology and genetics of polycystic ovary syndrome". Annals of the New York Academy of Sciences 997: 42–8. doi:10.1196/annals.1290.005. PMID 14644808. 
  • Haider SM, Patel JS, Poojari CS, Neidle S (July 2010). "Molecular modeling on inhibitor complexes and active-site dynamics of cytochrome P450 C17, a target for prostate cancer therapy". Journal of Molecular Biology 400 (5): 1078–098. doi:10.1016/j.jmb.2010.05.069. PMID 20595043. 

External links[edit]