Immunochemical evidence for multiple steroid-inducible hepatic cytochromes P-450 in the rat.
It has been established that there are glucocorticoid-inducible hepatic cytochromes P-450 in the rat (P-450p), the rabbit (LM3c) and man (HLp) which share extensive structural, functional and regulatory features. We prepared immunochemical probes to P-450p and identified a unique monoclonal antibody, 1G8, that recognizes purified P-450p, but neither purified LM3c nor HLp, on immunoblot analysis. The N-terminal amino acid sequence of purified samples of P-450p was identical with that previously reported for P-450PCN1 [Gonzalez, Nebert, Hardwick & Kasper (1985) J. Biol. Chem. 260, 7435-7441]. Immunoblot analyses of liver microsomes from untreated male rats revealed two 1G8-reactive proteins, whereas liver microsomes from untreated females contained none. Another monoclonal antibody, 13-7-10, reacted specifically with LM3c and HLp, but not with P-450p. A single 13-7-10-reactive microsomal protein was detected in untreated male and female rats, the latter protein exhibiting a greater apparent Mr. 1G8-reactive proteins were induced to the greatest extent by triacetyloleandomycin, followed by dexamethasone, chlordane, pregnenolone-16 alpha-carbonitrile and 2,4,2',4'-tetrachlorobiphenyl. In contrast, 13-7-10-reactive proteins were most strongly induced by dexamethasone, only moderately by triacetyloleandomycin and pregnenolone-16 alpha-carbonitrile, weakly by chlordane and not at all by 2,4,2',4'-tetrachlorobiphenyl. We conclude that the P-450p family in rat liver consists of three or more proteins that are structurally related and yet appear to be under distinct regulatory control.
Hostetler
K A
KA
Department of Pharmacology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298.
Wrighton
S A
SA
Kremers
P
P
Guzelian
P S
PS
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D007122:Immunoelectrophoresis; D007163:Immunosorbent Techniques; D007527:Isoenzymes / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D051381:Rats; D011919:Rats, Inbred Strains; D013256:Steroids / Q000494:pharmacology*
D000911:Antibodies, Monoclonal; D007527:Isoenzymes; D013256:Steroids; D003577:Cytochrome P-450 Enzyme System