Control of peptide-chain initiation in rat skeletal muscle

F. J. Kelly, L. S. Jefferson

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50 Scopus citations


A method was developed for isolation of native ribosomal subunits from rat gastrocnemius muscle. Native 40 S subunits which were isolated by this method retained their associated nonribosomal proteins and consisted primarily of particles with equilibrium densities of 1.41 and 1.48 g/cm3. Based on the binding of radiolabeled Met-tRNA(i)(Met), the 1.41 g/cm3 particle was identified as the 40 S initiation complex. Insulin deficiency in vivo resulting from either diabetes or fasting led to a 2-fold increase in 75 S monomers but had no effect on the numbers of native 40 and 60 S subunits or the relative distribution of the 1.41 and 1.48 g/cm3 particles. The rate of protein synthesis in perfused muscle preparations derived from insulin-deficient rats was reduced to about half the control value. Addition of insulin to the perfusate restored protein synthesis and 75 S monomers to control levels. The effect of insulin on protein synthesis was associated with a 1.5-fold increase in the amount of Met-tRNA(i)(Met) bound to the 1.41 g/cm3 particle. These findings identify formation of 40 S initiation complexes as a site of action of insulin on protein synthesis in skeletal muscle.

Original languageEnglish (US)
Pages (from-to)6677-6683
Number of pages7
JournalJournal of Biological Chemistry
Issue number11
StatePublished - 1985

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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