Phosphorylation of S-II is not affected by inhibitors of RNA synthesis

S-II is an essential factor for RNA polymerase II-mediated transcription. A phosphorylated form of S-II, termed S-II has been shown to be present in cells at half the concentration of S-II. In studies on the role of phosphorylation and dephosphorylation of S-II in transcription, the possibility that phosphorylation of S-II is coupled with transcription invivo was investigated. The phosphorylation of S-II was measured in mouse L cells cultured with two typical inhibitors of RNA synthesis. Neither of these inhibitors, 5, 6-dichloro-1-β-D-ribofuranosylbenzimidazole (DRB) and actinomycin D, affected the phosphorylation of S-II under conditions where 75 to 98% of RNA synthesis was inhibited at the initiation and elongation step, respectively. These results indicate that the phosphorylation of S-II and transcription are independent processes.