We provide here a list of 221 P450 genes and 12 putative pseudogenes that have been characterized as of December 14, 1992. These genes have been described in 31 eukaryotes (including 11 mammalian and 3 plant species) and 11 prokaryotes. Of 36 gene families so far described, 12 families exist in all mammals examined to date. These 12 families comprise 22 mammalian subfamilies, of which 17 and 15 have been mapped in the human and mouse genome, respectively. To date, each subfamily appears to represent a cluster of tightly linked genes. This revision supersedes the previous updates [Nebert et al., DNA 6, 1-11, 1987; Nebert et al., DNA 8, 1-13, 1989; Nebert et al., DNA Cell Biol. 10, 1-14 (1991)] in which a nomenclature system, based on divergent evolution of the superfamily, has been described. For the gene and cDNA, we recommend that the italicized root symbol "CYP" for human ("Cyp" for mouse), representing "cytochrome P450," be followed by an Arabic number denoting the family, a letter designating the subfamily (when two or more exist), and an Arabic numeral representing the individual gene within the subfamily. A hyphen should precede the final number in mouse genes. "P" ("p" in mouse) after the gene number denotes a pseudogene. If a gene is the sole member of a family, the subfamily letter and gene number need not be included. We suggest that the human nomenclature system be used for all species other than mouse. The mRNA and enzyme in all species (including mouse) should include all capital letters, without italics or hyphens. This nomenclature system is identical to that proposed in our 1991 update. Also included in this update is a listing of available data base accession numbers for P450 DNA and protein sequences. We also discuss the likelihood that this ancient gene superfamily has existed for more than 3.5 billion years, and that the rate of P450 gene evolution appears to be quite nonlinear. Finally, we describe P450 genes that have been detected by expressed sequence tags (ESTs), as well as the relationship between the P450 and the nitric oxide synthase gene superfamilies, as a likely example of convergent evolution.

No abstract

No abstract

We provide here a list of 154 P450 genes and seven putative pseudogenes that have been characterized as of October 20, 1990. These genes have been described in a total of 23 eukaryotes (including nine mammalian and one plant species) and six prokaryotes. Of 27 gene families so far described, 10 exist in all mammals. These 10 families comprise 18 subfamilies, of which 16 and 14 have been mapped in the human and mouse genomes, respectively; to date, each subfamily appears to represent a cluster of tightly linked genes. We propose here a modest revision of the initially proposed (Nebert et al., DNA 6, 1-11, 1987) and updated (Nebert et al., DNA 8, 1-13, 1989) nomenclature system based on evolution of the superfamily. For the gene we recommend that the italicized root symbol CYP for human (Cyp for mouse), representing cytochrome P450, be followed by an Arabic number denoting the family, a letter designating the subfamily (when two or more exist), and an Arabic numeral representing the individual gene within the subfamily. A hyphen should precede the final number in mouse genes. We suggest that the human nomenclature system be used for other species. This system is consistent with our earlier proposed nomenclature for P450 of all eukaryotes and prokaryotes, except that we are discouraging the future use of cumbersome Roman numerals.

No abstract