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 enzyme hydroxylates testosterone and dehydroepiandrosterone 3-sulphate, which is involved in the formation of estriol during pregnancy. The enzyme also metabolizes some drugs such as aflatoxin B1. This gene is part of a cluster of cytochrome P450 genes on chromosome 7q21.1. Transcript variants have been described, but it is not known whether these transcripts are normally produced. This gene undergoes readthrough transcription with the downstream CYP3AP1 pseudogene, resulting in an isoform with a novel C-terminus, as represented in GeneID:100861540. [provided by RefSeq, Feb 2012]