cytochrome P450 family 11 subfamily A member 1(CYP11A1) Homo sapiens This gene encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. This protein localizes to the mitochondrial inner membrane and catalyzes the conversion of cholesterol to pregnenolone, the first and rate-limiting step in the synthesis of the steroid hormones. Two transcript variants encoding different isoforms have been found for this gene. The cellular location of the smaller isoform is unclear since it lacks the mitochondrial-targeting transit peptide. [provided by RefSeq, Jul 2008],catalytic activity:Cholesterol + reduced adrenal ferredoxin + O(2) = pregnenolone + 4-methylpentanal + oxidized adrenal ferredoxin + H(2)O.,cofactor:Heme group.,disease:Defects in CYP11A1 are a cause of congenital adrenal insufficiency (CAI).,disease:Defects in CYP11A1 are a cause of congenital lipoid adrenal hyperplasia (CLAH) [MIM:201710], also called lipoid CAH. CLAH is the most severe form of adrenal hyperplasia. This autosomal recessive and potentially lethal condition includes the onset of profound adrenocortical insufficiency shortly after birth, hyperpigmentation reflecting increased production of pro-opiomelanocortin, elevated plasma renin activity as a consequence of reduced aldosterone synthesis, and male pseudohermaphroditism resulting from deficient fetal testicular testosterone synthesis. CLAH is a rare disease, except in Japan and Korea where it accounts for a significant percentage of cases of congenital adrenal hyperplasia.,function:Catalyzes the side-chain cleavage reaction of cholesterol to pregnenolone.,induction:By 8-bromo cyclic AMP.,pathway:Lipid metabolism, C21-steroid hormone metabolism.,similarity:Belongs to the cytochrome P450 family.,
