CYP17A1

Cytochrome P450 17A1, or steroid 17-alpha-monooxygenase, or 17α-hydroxylase/17,20 lyase/17,20 desmolase is an is_associated_with::enzyme that in humans is encoded by the CYP17A1 is_associated_with::gene. It is found in the zona reticularis of the adrenal cortex. This gene encodes a member of the is_associated_with::cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are is_associated_with::monooxygenases that catalyze many reactions involved in drug metabolism and synthesis of is_associated_with::cholesterol, is_associated_with::steroids, and other is_associated_with::lipids. This protein localizes to the is_associated_with::endoplasmic reticulum. It has both 17alpha-hydroxylase and 17,20-lyase activities, and is a key enzyme in the steroidogenic pathway that produces is_associated_with::progestins, is_associated_with::mineralocorticoids, is_associated_with::glucocorticoids, is_associated_with::androgens, and is_associated_with::estrogens.

More specifically, CYP17A1 acts upon is_associated_with::pregnenolone and is_associated_with::progesterone to add a is_associated_with::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 is_associated_with::lyase activity).

Clinical significance
Mutations in this gene are associated with 17 alpha-hydroxylase deficiency, is_associated_with::17 alpha-hydroxylase/17,20-lyase deficiency, is_associated_with::pseudohermaphroditism, and is_associated_with::adrenal hyperplasia.

The drug is_associated_with::abiraterone which is used to treat is_associated_with::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 is_associated_with::heme iron through its pyridine nitrogen, mimicking the subtrate.