These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Phenobarbital- and 3-methylcholanthrene-induced synthesis of two different molecular species of microsomal cytochrome P-450 in rat liver.
    Author: Harada N, Omura T.
    Journal: J Biochem; 1983 May; 93(5):1361-73. PubMed ID: 6885729.
    Abstract:
    The syntheses of two different molecular species of cytochrome P-450, P-450(PB), and P-450(MC), were examined using normal and drug-treated rats, and the rate of synthesis was correlated with the drug-induced increase of the amounts in the liver microsomes of treated animals. Phenobarbital (PB) and 3-methylcholanthrene (MC) were used as inducers. The syntheses of cytochrome b5 and NADPH-cytochrome P-450 reductase (fpT) were also examined. In vivo incorporation of L-[3H]leucine indicated a large increase of P-450(PB) synthesis in the livers of PB-treated animals, which reached a plateau value about 18-fold higher than the control level at 12 h. The synthesis of fpT was also stimulated by PB showing a peak value of 3 times the control at 12 h after PB administration, but it returned to the control level afterwards. On the other hand, the syntheses of P-450(MC) and cytochrome b5 did not change at all. Similarly, MC administration selectively induced the synthesis of P-450(MC), which was about 24 times the control at 6 h, whereas those of P-450(PB), cytochrome b5, and fpT were not affected by MC. Analysis of nascent peptides and in vitro translation of polysomes and total liver RNA prepared from control and drug-treated animals were also carried out, and the results of these in vitro experiments confirmed the observations in in vivo incorporation studies. It was found that both free and membrane-bound ribosomes participate in the syntheses of P-450(PB) and P-450(MC) in the case of control animals. PB and MC induced the syntheses of P-450(PB) and P-450(MC) by bound ribosomes but not by free ribosomes, and the contribution of bound ribosomes to the syntheses of these two species of cytochrome P-450 was predominant in the case of drug-treated animals. The molecular sizes of in vitro synthesized P-450(PB) and P-450(MC) were the same as those of authentic samples prepared from liver microsomes.
    [Abstract] [Full Text] [Related] [New Search]