title: Evidence for a new cytochrome P450 form induced by 3-methylcholanthrene in rats.
abstract: Evidence is presented for a new 3-methylcholanthrene (3MC)-induced form of cytochrome P450, P450MCX, in rat liver microsomes. P450MCX was co-purified with CYP1A1 from 3MC-treated male Sprague-Dawley rats but was resolved by gel electrophoresis. The M(r) of P450MCX (56,700) was intermediate between CYP1A1 (57,000) and CYP1A2 (54,800). Monoclonal antibodies showed that P450MCX was immunorelated to both CYP1A1 and CYP1A2 but not to CYP2B1, CYP2C6 or CYP3A1. Immunoreactive P450MCX was not detectable in liver microsomes from untreated rats but was highly induced by 3MC and Aroclor 1254, although not induced by isosafrole. The N-terminal amino acid sequence of P450MCX, obtained from an electroblotted sample resolved on SDS-PAGE, did not match any known cytochrome P450 or other protein. P450MCX may be a new member of the CYP1 family.
authors.affiliation: Department of Biomedical Sciences, University of Aberdeen Marischal College, U.K.
authors.forename: R J
authors.initials: RJ
authors.lastname: Weaver
authors.forename: B
authors.initials: B
authors.lastname: Dunbar
authors.forename: M
authors.initials: M
authors.lastname: Dickins
authors.forename: W T
authors.initials: WT
authors.lastname: Melvin
authors.forename: J
authors.initials: J
authors.lastname: Fothergill
authors.forename: M D
authors.initials: MD
authors.lastname: Burke
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001140:Aroclors / Q000494:pharmacology; D020111:Chlorodiphenyl (54% Chlorine); D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D004790:Enzyme Induction; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology*; D008862:Microsomes, Liver / Q000187:drug effects* / Q000201:enzymology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D001140:Aroclors; D020111:Chlorodiphenyl (54% Chlorine); D008748:Methylcholanthrene; D003577:Cytochrome P-450 Enzyme System