[Stimulation of the protein synthesizing capacity of thyroid gland polyribosomes in vitro under the influence of cyclic adenosine-3', 5'-monophosphate].

It was shown that cAMP increased the capacity of polyribosomes of the thyroid glands to the labeled phenylalanine incorporation into the protein by 51 per cent. Preincubation of microsomes or ribosomes with cAMP in the cell-free protein-synthesizing system also increased the incorporation of the labeled amino acids into the protein by 54 and 49 per cent, respectively. The optimal effect occurred with the concentration of cAMP of 0.2 mg/ml. cAMP in a concentration of 0.8 mg/ml inhibited the incorporation of the labeled amino acids by 32 per cent. This can possibly be attributed to the forming products of cAMP degradation. Modification of the protein-synthesizing system (ATP--1 mM. GTP--1.6 mM) led to the fact of an increase in the level of the labeled amino acid incorporation into the protein by 54 per cent; the simulating effect of cAMP persisted. In the absence of ATP in the incubation medium addition of cAMP failed to stimulate the protein synthesis. Thus, cAMP stimulated protein synthesis in the thyroid gland in vitro, with utilization of ribonucleoproteid particles.