Enhancement of the interferon-induced double-stranded RNA-dependent protein kinase activity by Sindbis virus infection and heat-shock stress.
In extracts of FL cells that were infected with Sindbis virus or treated with heat-shock stress, dsRNA-dependent phosphorylation of 77K protein was markedly increased. The 77K phosphoprotein was indistinguishable from the autophosphorylated and activated form of interferon (IFN)-induced dsRNA-dependent protein kinase (PK-I) by two-dimensional gel electrophoresis, and was immunologically related to P68 (Galabru, J. and Hovanessian, A., J. Biol. Chem. 262, 15538 (1987], the HeLa cell counterpart of PK-I. Immunoblotting experiments using monoclonal antibody against PK-I revealed that control cell extracts contained a substantial amount of PK-I protein, although they showed no measurable PK-I activity even when dsRNA was added. The amount of PK-I protein did not increase during a transient dsRNA-dependent enhancement of PK-I activity caused by Sindbis virus infection and heat-shock stress. This implies that the conversion of PK-I protein from a dsRNA-unresponsive form to a responsive form may be important in the regulation of PK-I activity. A similar mode of PK-I regulatory mechanism was operative in the early stages of IFN treatment, although after a prolonged treatment a net synthesis of the PK-I protein did take place.
Saito
S
S
Department of Measles Virus, National Institute of Health, Tokyo.
D002478:Cells, Cultured; D015180:Electrophoresis, Gel, Two-Dimensional; D004790:Enzyme Induction; D006358:Hot Temperature; D006801:Humans; D007370:Interferon Type I / Q000494:pharmacology*; D007700:Kinetics; D008970:Molecular Weight; D010750:Phosphoproteins / Q000032:analysis; D010766:Phosphorylation; D011233:Precipitin Tests; D011494:Protein Kinases / Q000378:metabolism*; D012845:Sindbis Virus / Q000187:drug effects / Q000201:enzymology*; D014036:Togaviridae Infections / Q000201:enzymology*; D019892:eIF-2 Kinase
D007370:Interferon Type I; D010750:Phosphoproteins; D011494:Protein Kinases; D019892:eIF-2 Kinase