cytochrome P450 family 17, subfamily A, polypeptide 1, and similar cytochrome P450s
This subfamily contains cytochrome P450 17A1 (CYP17A1 or Cyp17a1), cytochrome P450 21 (CYP21 or Cyp21) and similar proteins. CYP17A1, also called cytochrome P450c17, steroid 17-alpha-hydroxylase (EC 1.14.14.19)/17,20 lyase (EC 1.14.14.32), or 17-alpha-hydroxyprogesterone aldolase, catalyzes the conversion of pregnenolone and progesterone to their 17-alpha-hydroxylated products and subsequently to dehydroepiandrosterone (DHEA) and androstenedione; it catalyzes both the 17-alpha-hydroxylation and the 17,20-lyase reaction. This subfamily also contains CYP21, also called steroid 21-hydroxylase (EC 1.14.14.16) or cytochrome P-450c21 or CYP21A2, catalyzes the 21-hydroxylation of steroids and is required for the adrenal synthesis of mineralocorticoids and glucocorticoids. The CYP17A1-like subfamily belongs to the large cytochrome P450 (P450, CYP) superfamily of heme-containing proteins that catalyze a variety of oxidative reactions of a large number of structurally different endogenous and exogenous compounds in organisms from all major domains of life. CYPs bind their diverse ligands in a buried, hydrophobic active site, which is accessed through a substrate access channel formed by two flexible helices and their connecting loop.
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