Block in the elongation of protein synthesis in rabbit reticulocyte by action of the ionophore valinomycin.

In this paper we show that ribosomes isolated from cells inhibited for protein synthesis by the antibiotic ionophore Valinomycin can still support incorporation of [14C]-leucine into polypeptides in a cell-free system. The extent of this functional integrity depends upon the concentration of Valinomycin used and whether it acted as an ionophore or not. We demonstrate that the antibiotic acts on protein synthesis at the level of elongation and has no action either at the initiation level or as activating an RNase. Moreover, we show that it can inhibit protein synthesis at concentrations where its action as an ionophore cannot be detected.