[An inhibitor of translation in cellular mRNA containing the 100S structure from Krebs II ascites carcinoma cells infected with encephalomyocarditis virus].

As shown previously, the bulk of cellular mRNA in Krebs II ascite carcinoma cells infected with encephalomyocarditis virus during active virus-specific synthesis is bound to ribosomes within the 100S structure which is inactive in protein synthesis. In order to elucidate the reasons for the translation repression of cellular mRNA within the 100S structure, a fraction of loosely bound proteins which are liberated by treatment of the 100S structure with 0.5 M KCl an which contain sum translation factors, was obtained. This fraction was shown to contain an inhibitor which non-specifically represses the translation of endogenous viral and cellular mRNA within the composition of polyribosomes and of exogenous poly(A)-containing cellular mRNAs from ascite carcinoma cells.