In vitro protein synthesizing activity of rat liver as influenced by a physiological dose of cortisone and dibutyryl cyclic AMP

Effects of aminooxyacetate, alanine and other amino acids on protein synthesis in isolated rat hepatocytes

Protein synthesis in isolated rat hepatocytes has been measured by the incorporation of [14C]valine at high concentration and constant specific activity (5 mmol/l and 315 muCi/l). Protein synthesis was stimulated by the addition of an amino acid mixture, and by a number of individual amino acids alone, most notably alanine. Energy substrates (lactate, pyruvate) stimulated protein synthesis to the same extent as alanine, suggesting that a major part of the amino acid effect could be due to the provision of energy. Aminooxyacetate, an inhibitor of glutamate transaminases, inhibited protein synthesis strongly (70%), and abolished the stimulatory effects of alanine and energy substrates. This could indicate that hepatocytic protein synthesis is subject to positive control by a transamination-dependent agent.