EFFECT OF 7,12-DIMETHYLBENZ(A)ANTHRACENE ON BINDING OF AMINOACYL TRANSFER-RNA IN RAT-LIVER

  • 1 January 1977
    • journal article
    • research article
    • Vol. 37  (11) , 4220-4227
Abstract
Homogenates of the liver of female rats obtained 2 or 7 days, or 3 mo. after the i.v. injection of 7,12-dimethylbenz(a)anthracene were used to prepare ribosomes and postmicrosomal supernatant fractions and to prepare 0.5 M KCl salt wash fractions of the 40 S ribosomal subunits. The activity of the ribosomes was unchanged by 7,12-dimethylbenz(a)anthracene. The activity of the supernatant preparation, which contained limiting amounts of elongation factor 1 relative to elongation factor 2, in peptide synthesis was significantly increased 2 days but not 7 days after injection. Evidence was obtained that this increase was due to increased activity in binding phenylalanyl tRNA. The factor-dependent binding of methionyl tRNAfMet to control rat liver ribosomes was also markedly increased 2 days but not 7 days after injection. The liver of animals that bore mammary tumors 3 mo. after 7,12-dimethylbenz(a)anthracene injection also showed an increase in binding both aminoacyl tRNA species. The results are discussed in relation to the induction of liver drug-metabolizing enzymes and liver regeneration.