Inhibition of protein synthesis in reticulocytes by antibiotics: I. Effects on polysomes

Abstract

Several antibiotics have been tested for inhibition of protein synthesis: cycloheximide, streptovitacin A and pactamycin inhibit protein synthesis in intact reticulocytes and in a cell-free system prepared from reticulocytes. Sparsomycin inhibits protein synthesis in the cell-free system only. Cycloheximide and streptovitacin A, which are structurally related, presumably have a common mechanism of action. The inhibition by cycloheximide is reversible, while that by streptovitacin A seems to be completely irreversible. The difference in behavior of cycloheximide and streptovitacin A seems to be attributable to the fact that streptovitacin A does not diffuse out of reticulocytes, even though it readily enters these cells. Cycloheximide and streptovitacin A do not change the polysome pattern of reticulocyte lysate, nor cause the release of incomplete peptide chains. Pactamycin degrades the polysomes with the slow release of presumably completed peptide chains.