Ethanol-, fasting-, and acetone-inducible cytochromes P-450 in rat liver: regulation and characteristics of enzymes belonging to the IIB and IIE gene subfamilies

Biochemistry. 1988 Mar 22;27(6):1925-34. doi: 10.1021/bi00406a019.


Two major forms of hepatic microsomal cytochrome P-450 were purified from starved and acetone-treated rats. On the basis of amino acid sequence analysis, they were identified as P-450j and P-450b. Ethanol or acetone treatment of rats caused a 9-fold increase in the amount of P-450j in liver microsomes accompanied by similar increases in the rate of NADPH-dependent metabolism of carbon tetrachloride, acetone, and benzene. Immunological experiments indicated that P-450j constitutes the major catalyst of the microsomal metabolism of the latter agents and contributes by about 50% to microsomal P-450-dependent ethanol oxidation under the conditions used. The P-450j-dependent catalytic activities had a high rate of turnover. In contrast, this was not the case for the immunodetectable P-450j, indicating the occurrence of inactive forms of this protein in microsomes. Starvation or ethanol or acetone treatment caused 10-30-fold increases in the amount of both mRNA and apoprotein of P-450b,e compared to control. Run-on experiments and the concomitant increases of the P-450b,e gene products at the mRNA and protein levels indicated the appearance of mainly a transcriptional activation by acetone, ethanol, or starvation. Fasting exerted, in addition, a pronounced synergistic effect on acetone-dependent induction of P-450b,e mRNA (3-fold), apo-P-450b,e (4.3-fold), P-450j mRNA (2-fold), and apo-P-450j (2-fold). No increase of mRNA coding for P-450j, compared to control, was seen after acetone or ethanol treatment alone. The results indicate that effects of ethanol, acetone, and/or starvation on drug and xenobiotic metabolism are caused by the induction of P-450 forms belonging to at least two gene subfamilies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetone / pharmacology*
  • Amino Acid Sequence
  • Animals
  • Cytochrome P-450 Enzyme System / biosynthesis
  • Cytochrome P-450 Enzyme System / genetics*
  • Cytochrome P-450 Enzyme System / isolation & purification
  • Enzyme Induction
  • Ethanol / pharmacology*
  • Fasting
  • Genes* / drug effects
  • Isoenzymes / biosynthesis
  • Isoenzymes / genetics*
  • Isoenzymes / isolation & purification
  • Kinetics
  • Male
  • Microsomes, Liver / drug effects
  • Microsomes, Liver / enzymology*
  • Molecular Sequence Data
  • Rats
  • Rats, Inbred Strains


  • Isoenzymes
  • Acetone
  • Ethanol
  • Cytochrome P-450 Enzyme System