Cytochrome P450, family 3, subfamily A, also known as CYP3A, is a human

gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

locus. A homologous locus is found in mice. The CYP3A

locus Locus (plural loci) is Latin for "place". It may refer to: Entertainment * Locus (comics), a Marvel Comics mutant villainess, a member of the Mutant Liberation Front * ''Locus'' (magazine), science fiction and fantasy magazine ** ''Locus Award ...

includes all the known members of the 3A subfamily of the

cytochrome P450 Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various compo ...

superfamily of genes. These genes encode

monooxygenase Monooxygenases are enzymes that incorporate one hydroxyl group (−OH) into substrates in many metabolic pathways. In this reaction, the two atoms of dioxygen are reduced to one hydroxyl group and one H2O molecule by the concomitant oxidation ...

s which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. The CYP3A cluster consists of four genes: *

CYP3A4 Cytochrome P450 3A4 (abbreviated CYP3A4) () is an important enzyme in the body, mainly found in the liver and in the intestine. It oxidizes small foreign organic molecules ( xenobiotics), such as toxins or drugs, so that they can be removed from t ...

, *

CYP3A5 Cytochrome P450 3A5 is a protein that in humans is encoded by the ''CYP3A5'' gene. Tissue distribution ''CYP3A5'' encodes a member of the cytochrome P450 superfamily of enzymes. Like most of the cytochrome P450, the CYP3A5 is expressed in the ...

, *

CYP3A7 CYP3A7 is an enzyme belonging to the cytochrome P450 family. It is 503 amino acids in size and shares 87% of its sequence with CYP3A4. It carries out a similar role in fetuses that CYP3A4 serves in adults. The gene location is 7q22.1. The CYP3A g ...

, and *

CYP3A43 Cytochrome P450 3A43 is a protein that in humans is encoded by the ''CYP3A43'' gene. This gene encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved ...

. The region also contains four

pseudogene Pseudogenes are nonfunctional segments of DNA that resemble functional genes. Most arise as superfluous copies of functional genes, either directly by DNA duplication or indirectly by reverse transcription of an mRNA transcript. Pseudogenes are ...

s: * , * , * , and * . as well as several extra exons which may or may not be included in transcripts produced from this region. Previously another CYP3A member, CYP3A3, was thought to exist; however, it is now thought that this sequence represents a transcript variant of CYP3A4.

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Further reading