P450 SUPERFAMILY - UPDATE ON NEW SEQUENCES, GENE-MAPPING, ACCESSION NUMBERS AND NOMENCLATURE

We provide here a list of 481 P450 genes and 22 pseudogenes, plus all accession numbers that have been reported as of October 18, 1995. Thes e genes have been described in 85 eukaryote (including vertebrates, in vertebrates, fungi, and plants) and 20 prokaryote species. Of 74 gene families so far described, 14 families exist in all mammals examined t o date. These 14 families comprise 26 mammalian subfamilies, of which 20 and 15 have been mapped in the human genome and the mouse genome, r espectively. Each subfamily usually represents a cluster of tightly li nked genes widely scattered throughout the genome, but there are excep tions. Interestingly, the CYP51 family has been found in mammals, fila mentous fungi and yeast, and plants - attesting to the fact that this P450 gene family is very ancient. One functional CYP51 gene and two pr ocessed pseudogenes, which are the first examples of intronless pseudo genes within the P450 superfamily, have been mapped to three different human chromosomes. This revision supersedes the four previous updates in which a nomenclature system, based on divergent evolution of the s uperfamily, has been described. For the gene, we recommend that the it alicized root symbol 'CYP' for human ('Cyp' for mouse and Drosophila), representing 'cytochrome P450', be followed by an Arabic number denot ing the family, a letter designating the subfamily (when two or more e xist), and an Arabic numeral representing the individual gene within t he subfamily. A hyphen is no longer recommended in mouse gene nomencla ture. 'P' ('ps' in mouse and Drosophila) after the gene number denotes a pseudogene; 'X' after the gene number means its use has been discon tinued. If a gene is the sole member of a family, the subfamily letter and gene number would be helpful but need not be included. The human nomenclature system should be used for all species other than mouse an d Drosophila. The cDNAs, mRNAs and enzymes in all species (including m ouse) should include all capital letters, and without italics or hyphe ns. This nomenclature system is similar to that proposed in our previo us updates.