A cytochrome P450 monooxygenase involved in the metabolism of steroid hormones and vitamins (PubMed:2732228, PubMed:10681376, PubMed:11093772, PubMed:12865317). 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 (NADPH--hemoprotein reductase). Catalyzes the hydroxylation of carbon-hydrogen bonds (PubMed:12865317, PubMed:2732228, PubMed:10681376, PubMed:11093772). Exhibits high catalytic activity for the formation of catechol estrogens from 17beta-estradiol (E2) and estrone (E1), namely 2-hydroxy E1 and E2 (PubMed:12865317). Catalyzes 6beta-hydroxylation of the steroid hormones testosterone, progesterone, and androstenedione (PubMed:2732228). Catalyzes the oxidative conversion of all-trans-retinol to all-trans-retinal, a rate-limiting step for the biosynthesis of all-trans-retinoic acid (atRA) (PubMed:10681376). Further metabolizes all trans-retinoic acid (atRA) to 4-hydroxyretinoate and may play a role in hepatic atRA clearance (PubMed:11093772). Also involved in the oxidative metabolism of xenobiotics, including calcium channel blocking drug nifedipine and immunosuppressive drug cyclosporine (PubMed:2732228). an organic molecule + O2 + reduced [NADPH--hemoprotein reductase] = an alcohol + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] 17beta-estradiol + O2 + reduced [NADPH--hemoprotein reductase] = 2-hydroxy-17beta-estradiol + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] 17beta-estradiol + O2 + reduced [NADPH--hemoprotein reductase] = 4-hydroxy-17beta-estradiol + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] estrone + O2 + reduced [NADPH--hemoprotein reductase] = 2-hydroxyestrone + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] estrone + O2 + reduced [NADPH--hemoprotein reductase] = 4-hydroxyestrone + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] O2 + reduced [NADPH--hemoprotein reductase] + testosterone = 6beta,17beta-dihydroxyandrost-4-en-3-one + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] androst-4-ene-3,17-dione + O2 + reduced [NADPH--hemoprotein reductase] = 6beta-hydroxyandrost-4-ene-3,17-dione + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] O2 + progesterone + reduced [NADPH--hemoprotein reductase] = 6beta-hydroxyprogesterone + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] all-trans-retinol + O2 + reduced [NADPH--hemoprotein reductase] = all-trans-retinal + H(+) + 2 H2O + oxidized [NADPH--hemoprotein reductase] all-trans-retinoate + O2 + reduced [NADPH--hemoprotein reductase] = all-trans-4-hydroxyretinoate + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] Steroid hormone biosynthesis. Cofactor metabolism; retinol metabolism. By glucocorticoids, such as dexamethesone. Chimeric transcripts, characterized by CYP3A43 exon 1 joined at canonical splice sites to distinct sets of CYP3A5 exons, have been detected. All are possibly produced by trans-splicing. The chimeric transcripts exist in 2 different combinations: CYP3A43 exon 1 joined in frame to CYP3A5 exon 11-13 and CYP3A43 exon 1 joined in frame to CYP3A5 exon 12-13. All chimeric transcripts are expressed at very low levels in the liver (PubMed:11726664). Belongs to the cytochrome P450 family. CYP3A5 alleles