Purification of a factor that restores translation of vesicular stomatitis virus mRNA in extracts from poliovirus-infected HeLa cells.
It was previously shown that the poliovirus-induced inhibition of translation of capped mRNAs can be reversed by a protein found in preparations of the eukaryotic initiation factor eIF-4B [Rose, J. K., Trachsel, H., Leong, K. & Baltimore, D. (1978) Proc. Natl. Acad. Sci. USA 75, 2732--2736]. This "restoring factor" has now been purified from a high-salt wash of rabbit reticulocyte ribosomes by taking advantage of its tight association with factor eIF-3 at low salt concentrations. It did not copurify with the major Mr 80,000 polypeptide of eIF-4B preparations but did copurify with a Mr 24,000 polypeptide previously shown to bind to the cap structures of mRNAs [Sonenberg, N., Rupprecht, K. M., Hecht, S. M. & Shatkin, A. J. (1979) Proc. Natl. Acad. Sci. USA 76, 4345--4349]. Both the electrophoretic mobility and the tryptic peptide pattern of the restoring factor were indistinguishable from those of the cap-binding protein, and the restoring factor could be crosslinked to the 5'-terminal cap on mRNA. Thus, is appears that poliovirus inhibits cellular protein synthesis by inactivation of some crucial property of the cap-binding protein.
D002352:Carrier Proteins / Q000378:metabolism; D002474:Cell-Free System; D006367:HeLa Cells / Q000378:metabolism*; D006801:Humans; D008970:Molecular Weight; D010446:Peptide Fragments; D010448:Peptide Initiation Factors / Q000378:metabolism*; D017955:Poliovirus / Q000235:genetics*; D014176:Protein Biosynthesis; D014721:Vesicular stomatitis Indiana virus / Q000235:genetics*
D002352:Carrier Proteins; D010446:Peptide Fragments; D010448:Peptide Initiation Factors