The P450 Superfamily: Updated Listing of All Genes and Recommended Nomenclature for the Chromosomal Loci

Abstract

In this update we provide a list of the 71 P450 genes and the four P450 pseudogenes that have been characterized as of September 30, 1988. The chromosomal locations of many of these genes are also summarized. A modest revision of the initially proposed nomenclature of the P450 superfamily (Nebert et al., DNA 6, 1-11, 1987) is described specifically for the human and mouse chromosomal loci. The motivation for this revision is to conform to the rules of nomenclature for human and mouse genes. Recommendations for the naming of chromosomal loci include the root symbol "CYP" for human ("Cyp" for mouse), denoting "cytochrome P450." We recommend that this root also be used for other organisms. For a chromosomal locus, the root symbol is followed by an Arabic numeral designating the P450 family, a letter indicating the subfamily, and an Arabic numeral representing the individual gene within the family or subfamily. Numbers of the individual genes usually will be assigned in the order the genes are identified. This system is consistent with our earlier proposed nomenclature for P450 families and gene products from all eukaryotes and prokaryotes.

Expression of cytochrome P450IA in breast cancer

“…The cytochromes P450 are a multigene super-family of enzymes, existing as multiple forms, which metabolise a wide variety of xenobiotics and endogenous compounds including steroid hormones and arachidonic acid (Gonzalez, 1990;Nebert & Gonzalez, 1987;Nebert et al, 1989;Fitzpatrick & Murphy, 1988). This group of enzymes has a central role in activating and detoxifying chemical carcinogens and anticancer drugs (Guengerich, 1988).…”

Effect of cyclophosphamide on serum cyclosporine levels at the conditioning of hematopoietic stem cell transplantation

“…24,25 CY3A4 is the primary hepatic enzyme that metabolizes CsA, and it may contribute to a reduction in Effect of CY at conditioning on serum CsA levels serum CsA levels. 9,10 Longitudinal analysis showed that a significant difference of increment in serum CsA levels was observed at day 0 of HSCT. As autoinduction of CY generally begins within 24 h of CY administration, this rapid progression could explain the occurrence of this early significant difference.…”

“…9,37 Metabolites of CsA are excreted into the bile. 10 Less than 1% of CsA is excreted in an unchanged form in urine. Another metabolic pathway involves P-glycoprotein, which is a membrane efflux pump that keeps intracellular drug concentrations low by transporting the drug out of the cell.…”

“…4 In P-450 enzymes, P-450 3A4 predominantly metabolizes CsA, and this enzyme family is subjected to both induction and inhibition by several agents. 9,10 Induction occurs when a drug induces or accelerates another drug's metabolism by P-450 enzymes. Inhibition occurs when two different drugs require metabolism by the same P-450 enzyme and compete for binding and metabolism by that enzyme.…”

Glycine N-Methyltransferase Is an Example of Functional Diversity

“…In addition, these substances are potent inducers of certain biotransformation reactions that are catalyzed by the cytochrome P-450-dependent monooxygenases, a super family of isozymic hemoproteins comprising more than 12 gene groups (8). These isozymes display broad substrate specificity and metabolize both endogenous substrates and xenobiotics to electrophilic derivatives, some of which can interact with DNA, thereby potentially activating protooncogenes or inactivating tumor suppressor genes.…”