PHOSPHORYLATION OF THE C-TERMINAL DOMAIN OF RNA-POLYMERASE-II BY THE EXTRACELLULAR-SIGNAL-REGULATED PROTEIN-KINASE ERK2

Rat ERK2, an extracellular-signal-regulated protein kinase family memb er, phosphorylates RNA polymerase II in vitro. Phosphorylation occurs within the heptapeptide repeats of the C-terminal domain of the larges t subunit, in a region important for regulation of transcriptional act ivity. Analysis of deletion mutants and synthetic peptides showed that ERK2 phosphorylation occurrs at multiple serine residues throughout t he C-terminal domain, with no marked preference for consensus repeats versus naturally occurring variants. Our results are consistent with t he idea that protein kinases in the extracellular-signal-regulated pro tein kinase family regulate transcription by direct phosphorylation of RNA polymerase II, but do not support a model where particular portio ns of the C-terminal domain are special targets of ERK phosphorylation . (C) 1995 Academic Press, Inc.