Potyribosomes Active in Reticulocyte Protein Synthesis

protein synthesis proceeds primarily on polyribo-somes which are clusters of 2 or more ribosomes. It has been proposed that the polyribosomes are com-posed of a number of 78S ribosomes attached to a strand of messenger-RNA along which they move as the peptide chain grows. One of the initial problems addressed by the present investigations was to determine the pro-portion of ribosomes arranged as polyribosomes in the cell. For these studies reticulocytes were pre