Activation of double-stranded RNA-activated protein kinase in HeLa cells after poliovirus infection does not result in increased phosphorylation of eucaryotic initiation factor-2.
Protein kinase activity in general is stimulated at least 5- to 10-fold in ribosomal salt wash preparations from poliovirus-infected HeLa cells compared with those from mock-infected cells. The stimulation of kinase activity is manifested by increased phosphorylation of ribosome-associated polypeptides having approximate molecular weights of 135,000, 120,000, 85,000, 68,000, 65,000, 40,000, 28,000, 25,000, and 21,000. The Mr 68,000 phosphoprotein is structurally identical to the interferon-induced, double-stranded RNA-activated protein kinase (P1) which phosphorylates the alpha subunit of eucaryotic initiation factor-2 (eIF-2). A similar protein of Mr 68,000 is more phosphorylated in poliovirus-infected cells than in mock-infected cells. Increased phosphorylation of P1 protein in poliovirus-infected cells, however, does not result in an increased phosphorylation of the alpha subunit of endogenous or exogenously added eIF-2, both in vitro and in vivo. These results suggest that a mechanism must exist in poliovirus-infected HeLa cells which prevents further phosphorylation of eIF-2 by the activated kinase.
D004789:Enzyme Activation / Q000187:drug effects; D015852:Eukaryotic Initiation Factor-2; D006367:HeLa Cells / Q000378:metabolism; D006801:Humans; D010448:Peptide Initiation Factors / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010766:Phosphorylation; D017955:Poliovirus / Q000502:physiology*; D011494:Protein Kinases / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D012330:RNA, Double-Stranded / Q000494:pharmacology*; D019892:eIF-2 Kinase
D015852:Eukaryotic Initiation Factor-2; D010448:Peptide Initiation Factors; D011506:Proteins; D012330:RNA, Double-Stranded; D011494:Protein Kinases; D019892:eIF-2 Kinase; D010744:Phosphoric Monoester Hydrolases