The binding of tritiated elongation-factors 1 and 2 to ribosomes from Krebs II mouse ascites-tumore cells. The influence of various antibiotics and toxins.

The effect of a number of different antibiotics and toxins on the capacity of Krebs II mouse ascites ribosomes to bind 3H-labelled elongation factors (EF-1 and EF-2) has been examined. It was found that abrin and ricin inhibit the binding of EF-2, while diphtheria toxin, sparsomycin, streptovitacin A, and cycloheximide had essentially no effect on its binding. Of the other compounds examined, sparsomycin was unique in its capacity, under some circumstances, to significantly affect the binding of aminoacyl-tRNA and EF-1 to ribosomes. Fusidic acid appears to nonspecifically enhance the binding of both EF-1 and EF-2.