cytochrome P450 family 26, subfamily A, polypeptide 1
Cytochrome P450s 26A1 (CYP26A1) is a retinoic acid-metabolizing cytochrome that plays key roles in retinoic acid (RA) metabolism. It is the main all-trans-retinoic acid (atRA) hydroxylase that catalyzes the formation of several hydroxylated forms of RA, including 4-OH-RA, 4-oxo-RA and 18-OH-RA. RA is a critical signaling molecule that regulates gene transcription and the cell cycle. CYP26A1 has been shown to upregulate fascin and promote the malignant behavior of breast carcinoma cells. It 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.