Protein Synthesis and Polyribosomes in the Calf Lens

A cell-free system capable of incorporating amino acid into protein has been isolated from calf lens. Polyribosomes have been shown to be present in the ribosomal fraction and to be responsible for most of the protein-synthesizing capacity of this fraction. The polyribosomes have been examined by electron microscopy and appear to be composed of long strands of ribonucleic acid, ranging from 7,000 A to 20,000 A, and containing a large number of ribosomes with an average diameter of about 140 A.