Further evidence that elongation factor 1 remains bound to ribosomes during peptide chain elongation.

This paper describes three types of experiments which indicate that the binding sites for elongation factor 1 (EF-1) and elongation factor 2 (EF-2) on ascites cell ribosomes are not identical and perhaps not even overlapping. The experimental evidence presented includes direct competitive binding of labeled elongation factors to ribosomes as well as the influence of pokeweed antiviral protein and Escherichia coli anti L7/L12 proteins on the binding and function of the two factors. It is further shown that EF-1beta from Artemia salina does not function in displacing EF-1 from mouse ascites tumor cell ribosomes. These results also support our recently proposed model that EF-1 remains bound to the ribosome during the peptide chain elongation cycle.