Opposing effects of Ctk1 kinase and Fcp1 phosphatase at Ser 2 of the RNA polymerase II C-terminal domain

Eun Jung Cho, Michael S. Kobor, Minkyu Kim, Jack Greenblatt, Stephen Buratowski

Research output: Contribution to journalArticlepeer-review

342 Scopus citations


The C-terminal domain (CTD) of the RNA polymerase II (Pol II) largest subunit is hyperphosphorylated during transcription. Using an in vivo cross-linking/chromatin immunoprecipitation assay, we found previously that different phosphorylated forms of RNA Pol II predominate at different stages of transcription. At promoters, the Pol II CTD is phosphorylated at Ser 5 by the basal transcription factor TFIIH. However, in coding regions, the CTD is predominantly phosphorylated at Ser 2. Here we show that the elongation-associated phosphorylation of Ser 2 is dependent upon the Ctk1 kinase, a putative yeast homolog of Cdk9/P-TEFb. Furthermore, mutations in the Fcp1 CTD phosphatase lead to increased levels of Ser 2 phosphorylation. Both Ctk1 and Fcp1 cross-link to promoter and coding regions, suggesting that they associate with the elongating polymerase. Both Ctk1 and Fcp1 have been implicated in regulation of transcription elongation. Our results suggest that this regulation may occur by modulating levels of Ser 2 phosphorylation, which in turn, may regulate the association of elongation factors with the polymerase.

Original languageEnglish (US)
Pages (from-to)3319-3329
Number of pages11
JournalGenes and Development
Issue number24
StatePublished - Dec 15 2001
Externally publishedYes


  • MRNA capping enzyme
  • MRNA processing
  • Phosphorylation
  • RNA polymerase II
  • Transcription

ASJC Scopus subject areas

  • Genetics
  • Developmental Biology


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