The C-terminal domain phosphatase and transcription elongation activities of FCP1 are regulated by phosphorylation

Proc Natl Acad Sci U S A. 2003 Mar 4;100(5):2328-33. doi: 10.1073/pnas.2628049100. Epub 2003 Feb 18.


The C-terminal domain (CTD) of the largest subunit of RNA polymerase II (RNAPII) is heavily phosphorylated during the transition from transcription initiation to the establishment of an elongation-competent transcription complex. FCP1 is the only phosphatase known to be specific for the CTD of the largest subunit of RNAPII, and its activity is believed to be required to reactivate RNAPII, so that RNAPII can enter another round of transcription. We demonstrate that FCP1 is a phosphoprotein, and that phosphorylation regulates FCP1 activities. FCP1 is phosphorylated at multiple sites in vivo. The CTD phosphatase activity of phosphorylated FCP1 is stimulated by TFIIF, whereas dephosphorylated FCP1 is not. In addition to its role in the recycling of RNAPII, FCP1 also affects transcription elongation. Phosphorylated FCP1 is more active in stimulating transcription elongation than the dephosphorylated form of FCP1. We found that only phosphorylated FCP1 can physically interact with TFIIF. We set out to purify an FCP1 kinase from HeLa cells and identified casein kinase 2, which, surprisingly, displayed a negative effect on FCP1-associated activities.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alkaline Phosphatase / metabolism
  • Animals
  • Baculoviridae / metabolism
  • Base Sequence
  • Blotting, Western
  • Casein Kinase II
  • Cell Line
  • Cell Nucleus / metabolism
  • Gene Expression Regulation*
  • HeLa Cells
  • Humans
  • Insecta
  • Molecular Sequence Data
  • Phosphoprotein Phosphatases / chemistry*
  • Phosphorylation
  • Precipitin Tests
  • Protein Structure, Tertiary
  • Protein-Serine-Threonine Kinases / metabolism
  • RNA Polymerase II / chemistry*
  • RNA Polymerase II / metabolism
  • Transcription, Genetic


  • Casein Kinase II
  • Protein-Serine-Threonine Kinases
  • RNA Polymerase II
  • Alkaline Phosphatase
  • Phosphoprotein Phosphatases
  • carboxy-terminal domain phosphatase