title: Translational barrier in central region of encephalomyocarditis virus genome. Modulation by elongation factor 2 (eEF-2).
abstract: A fractionated cell-free system from Krebs-2 cells was prepared which contained ribosomes and a high-speed supernatant. When this system was programmed with encephalomyocarditis virus RNA, the synthesis of a precursor of capsid proteins, polypeptide preA, proceeded at a rate not very different from that observed in unfractionated extracts, whereas the synthesis of more distally encoded proteins, in particular polypeptide F, was greatly retarded, if not abolished. A protein was purified from the cytoplasmic extracts of Krebs-2 cells which greatly enhanced production of polypeptide F as well as other noncapsid proteins in the fractionated system. By several criteria, this protein was identified as eukaryotic elongation factor 2 (eEF-2). By using the ADP-ribosylation assay, it was found that the fractionated system contained about 15% of the amount of eEF-2 present in the unfractionated extracts. The results suggest that changes in the eEF-2 content may affect the elongation rate differently at different regions of the RNA template.
mesh_terms: D002474:Cell-Free System; D004686:Encephalomyocarditis virus / Q000235:genetics* / Q000378:metabolism; D005814:Genes, Viral; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors / Q000302:isolation & purification / Q000502:physiology*; D010455:Peptides / Q000302:isolation & purification; D014176:Protein Biosynthesis; D012367:RNA, Viral / Q000302:isolation & purification; D014764:Viral Proteins / Q000096:biosynthesis
chemical_list: D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors; D010455:Peptides; D012367:RNA, Viral; D014764:Viral Proteins