Regulation of protein turnover by glucose, insulin, and amino acids in adipose tissue

M. E. Tischler, A. H. Ost, B. Spina

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Protein synthesis and degradation were measured simultaneously in epididymal fat pads of rats by use of the incorporation of [14C]phenylalanine into protein and the sum of net protein breakdown and protein synthesis, respectively. Neither glucose nor insulin altered protein synthesis, but together they promoted this process; pyruvate could be substituted for glucose. Separately, glucose or insulin diminished proteolysis, and these effects were additive. In the presence of glucose and insulin, leucine, alanine, glutamine, glutamate, and aspartate lowered protein degradation to varying degrees but did not alter protein synthesis. Glutamate, but not leucine or alanine, was inhibitory without glucose and insulin present. When aminooxyacetic acid was provided to decrease the rate of transamination of amino acids, the inhibitory effects of leucine, alanine, and aspartate, but not of glutamate, appeared to be diminished. α-Ketoglutarate, but neither α-ketoisocaproate nor pyruvate, could diminish proteolysis. Inhibition of proteolysis was associated with a higher tissue content of glutamate and a greater production of glutamate and glutamine. These results suggest that glutamate itself may inhibit proteolysis in adipose tissue and mediate, at least in part, the effects of other amino acids.

Original languageEnglish (US)
Pages (from-to)C228-C233
JournalAmerican Journal of Physiology - Cell Physiology
Issue number2
StatePublished - 1984

ASJC Scopus subject areas

  • Physiology
  • Cell Biology


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