cytochrome P450 family 26, subfamily B, polypeptide 1
Cytochrome P450 26B1 (CYP26B1) is a retinoic acid-metabolizing cytochrome that plays key roles in retinoic acid (RA) metabolism. It is an all-trans-retinoic acid (atRA) hydroxylase that catalyzes the formation of similar metabolites as CYP26A1. RA is a critical signaling molecule that regulates gene transcription and the cell cycle. In rats, CYP26B1 regulates sex-specific timing of meiotic initiation, independent of RA signaling. CYP26B1 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.