[Heterogeniety of the amino acid pool for protein synthesis in Ehrlich ascites carcinoma cells].

Using a new methodological approach based on a step-wise labelling with [14C] and [3H] amino acids, it was demonstrated that the Ehrlich ascite carcinoma cells are capable of utilizing both intracellular and extracellular amino acid pools for protein synthesis. The inhibition of amino acid transport into the cells is accompanied by a more intensive utilization of the exogenous pool. The described procedure permits to calculate the specific radioactivity of the tRNA-bound amino acid and the absolute rate of protein synthesis.