A cytochrome P450 monooxygenase involved in the metabolism of endogenous oxysterols and steroid hormones, including neurosteroids (PubMed:10588945, PubMed:24491228). Mechanistically, uses molecular oxygen inserting one oxygen atom into a substrate, and reducing the second into a water molecule, with two electrons provided by NADPH via cytochrome P450 reductase (CPR; NADPH-ferrihemoprotein reductase) (PubMed:10588945, PubMed:24491228). Catalyzes the hydroxylation of carbon hydrogen bonds of steroids with a preference for 7-alpha position (PubMed:10588945, PubMed:24491228). Usually metabolizes steroids carrying a hydroxy group at position 3, functioning as a 3-hydroxy steroid 7-alpha hydroxylase (PubMed:24491228). Hydroxylates oxysterols, including 25-hydroxycholesterol and (25R)-cholest-5-ene-3beta,26-diol toward 7-alpha hydroxy derivatives, which may be transported to the liver and converted to bile acids (PubMed:9802883, PubMed:10588945). Via its product 7-alpha,25-dihydroxycholesterol, a ligand for the chemotactic G protein-coupled receptor GPR183/EBI2, regulates B cell migration in germinal centers of lymphoid organs, thus guiding efficient maturation of plasma B cells and overall antigen-specific humoral immune response (By similarity). 7-alpha hydroxylates neurosteroids, including 3beta-hydroxyandrost-5-en-17-one (dehydroepiandrosterone) and pregnenolone, both involved in hippocampus-associated memory and learning (PubMed:24491228). Metabolizes androstanoids toward 6- or 7-alpha hydroxy derivatives (PubMed:24491228). 25-hydroxycholesterol + O2 + reduced [NADPH--hemoprotein reductase] = 7alpha,25-dihydroxycholesterol + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] (25R)-cholest-5-ene-3beta,26-diol + O2 + reduced [NADPH--hemoprotein reductase] = (25R)-cholest-5-en-3beta,7alpha,26-triol + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] (24S)-hydroxycholesterol + O2 + reduced [NADPH--hemoprotein reductase] = (24S)-7alpha-dihydroxycholesterol + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] (24S)-25-epoxycholesterol + O2 + reduced [NADPH--hemoprotein reductase] = (24S,25)-epoxy-7alpha-hydroxycholesterol + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] (22R)-hydroxycholesterol + O2 + reduced [NADPH--hemoprotein reductase] = (22R,7alpha)-dihydroxycholesterol + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] androst-5-en-3beta,17beta-diol + O2 + reduced [NADPH--hemoprotein reductase] = androst-5-en-3beta,7alpha,17beta-triol + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] 5alpha-androstane-3beta,17beta-diol + O2 + reduced [NADPH--hemoprotein reductase] = 5alpha-androstane-3beta,6alpha,17beta-triol + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] 3beta-hydroxyandrost-5-en-17-one + O2 + reduced [NADPH--hemoprotein reductase] = 3beta,7alpha-dihydroxyandrost-5-en-17-one + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] 3beta-hydroxy-5alpha-androstan-17-one + O2 + reduced [NADPH--hemoprotein reductase] = 3beta,7alpha-dihydroxy-5alpha-androstan-17-one + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] O2 + pregnenolone + reduced [NADPH--hemoprotein reductase] = 7alpha-hydroxypregnenolone + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] Inhibited by drugs voriconazole and metyrapone. Lipid metabolism; bile acid biosynthesis. Steroid hormone biosynthesis. Widely expressed. Expressed in brain, testis, ovary, prostate, liver, colon, kidney, small intestine, thymus and spleen. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Belongs to the cytochrome P450 family.