cytochrome P450 family 7, subfamily A, polypeptide 1
Cytochrome P450 7A1 (CYP7A1) is also called cholesterol 7-alpha-monooxygenase (EC 188.8.131.52) or cholesterol 7-alpha-hydroxylase. It catalyzes the hydroxylation at position 7 of cholesterol, a rate-limiting step in the classic (or neutral) pathway of cholesterol catabolism and bile acid biosynthesis. It is important for cholesterol homeostasis. CYP7A1 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.