Synthesis and cleavage of virus-specifici proteins in Krebs II carcinoma cells infected with encephalomyocarditis virus.

Abstract

Synthesis and cleavage of proteins in actinomycin D treated encephalomyocarditis virus-infected Krebs II cells were studied by acrylamide gel electrophoresis. In extracts of the infected cells, 8 major and at least 3 minor peptides of molecular weights ranging from 13×103 to 100×103 daltons, were discerned. Two of them were identified as structural proteins of the virion, one structural protein being absent from the cell extracts. High molecular weight proteins were shown to be precursors of other, stable peptides. These high molecular weight precursors, but not stable proteins, could be degraded by enzymes present in the extracts of infected or non-infected cells. The products of degradation differed, however, from those obtained during the cleavagein vivo. The processing of the precursor proteins in the cell was inhibited by diisopropyl fluorophosphate while the degradationin vitro was relatively insensitive to the drug.