Source:http://linkedlifedata.com/resource/umls/id/C1522419
NCI: Encoded by human CYP21A2 Gene (Cytochrome P450 Family), 494-aa 56-kDa Cytochrome P450 XXIB is a membrane-bound endoplasmic reticulum P450 heme-thiolate monooxygenase that hydroxylates steroids at the 21 position and is required for synthesis of steroid hormones including cortisol and aldosterone. The leucine-rich hydrophobic N-terminal region may anchor the protein. CYP21A2 defects cause congenital adrenal hyperplasia (CAH). Gene conversion events involving CYP21A2 and a nearby pseudogene are thought to account for many cases of steroid 21-hydroxylase deficiency. P450 enzymes catalyze reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. (NCI)