Effect of Emetine on Ribouncleic Acid Biosynthesis in HeLa Cells

Emetine inhibits RNA synthesis in HeLa cells. This inhibition was found to be dose‐dependent and exhibited a target‐size effect. The synthesis of pre‐rRNA, and the 28 S and 18 S ribosomal RNA species was affected by low concentrations of the drug (0.1 to 1 μM) emetine, a concentration that inhibited 80–85% of [ 3 H]uridine incorporation into RNA and abolished all rRNA synthesis, was studied further. The onset of RNA inhibition by the drug was immediate, but some residual RNA synthesis continued linerly for the first 90 min and then stopped. The inhibitory effect of emetine was intially reversible after removal of the drug, but RNA synthesis eventually stopped due to the irreversible inhibitory effect of emetine on protein synthesis. The possible mode of action of emetine on RNA synthesis and its use in the study of prokaryotic obligate parasites of eukaryotic cells are discussed.