Phosphorylation of S-II, a eukaryotic transcription factor, by casein kinase II.

Recently, casein kinase II was suggested to play a role in accurate transcription in vitro (R. Zandomeni, M. C. Zandomeni, D. Shungar, and R. Weinmann, J. Biol. Chem., 261, 3414 (1986)). In the present study, we examined whether transcription factor S-II is a target of casein kinase II, because the phosphorylated form of S-II, termed S-II', is known to be present in vivo. We found that S-II was phosphorylated by casein kinase II purified from Ehrlich ascites tumor cells, and showed that this reaction was inhibited by 5,6-dichloro-1-ƒÀ-D-ribofuranosylbenzimidazole (DRB). DRB also inhibited accurate transcription of the adenovirus major late gene in a nuclear lysate of Ehrlich ascites tumor cells, as it has .been found to do in a HeLa cell lysate. This inhibition of transcription was partly restored by addition of purified casein kinase II, but not S-II', to the reaction mixture.