Studies on the Role of Ribosomes in the Regulation of Protein Synthesis in Hypophysectomized and Thyroidectomized Rats

Abstract

Abstract Polyribosomes were obtained from the livers of hypophysectomized and control rats. Although sucrose gradient analysis disclosed that polyribosome profiles of the livers of hypophysectomized animals were identical with those of livers derived from intact controls, the rate of amino acid incorporation into hepatic protein in vitro was lower in the polyribosomes derived from hypophysectomized animals. Furthermore, the stimulation of phenylalanine-14C incorporation that followed the addition of polyuridylic acid was less when the disaggregated polyribosomes were obtained from hypophysectomized rats than when similar preparations obtained from control animals were used. Similar findings were obtained with polyribosomes from thyroidectomized rats. These studies suggest that hypophysectomy and thyroidectomy influence protein synthesis predominantly by action at the level of the ribosome.