Ser7 phosphorylation of the CTD recruits the RPAP2 Ser5 phosphatase to snRNA genes

Mol Cell. 2012 Jan 13;45(1):111-22. doi: 10.1016/j.molcel.2011.11.006. Epub 2011 Dec 1.


The carboxy-terminal domain (CTD) of the large subunit of RNA polymerase II (Pol II) comprises multiple heptapeptide repeats of the consensus Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7. Reversible phosphorylation of Ser2, Ser5, and Ser7 during the transcription cycle mediates the sequential recruitment of transcription/RNA processing factors. Phosphorylation of Ser7 is required for recruitment of the gene type-specific Integrator complex to the Pol II-transcribed small nuclear (sn)RNA genes. Here, we show that RNA Pol II-associated protein 2 (RPAP2) specifically recognizes the phospho-Ser7 mark on the Pol II CTD and also interacts with Integrator subunits. siRNA-mediated knockdown of RPAP2 and mutation of Ser7 to alanine cause similar defects in snRNA gene expression. In addition, we show that RPAP2 is a CTD Ser5 phosphatase. Taken together, our results indicate that during transcription of snRNA genes, Ser7 phosphorylation facilitates recruitment of RPAP2, which in turn both recruits Integrator and dephosphorylates Ser5.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Carrier Proteins / chemistry
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Humans
  • Molecular Sequence Data
  • Phosphorylation
  • Protein Interaction Mapping
  • Protein Structure, Tertiary
  • RNA Polymerase II / chemistry*
  • RNA Polymerase II / metabolism
  • RNA Polymerase II / physiology
  • RNA, Small Nuclear / genetics*
  • Serine / metabolism*
  • Transcription, Genetic


  • Carrier Proteins
  • RNA, Small Nuclear
  • RPAP2 protein, human
  • Serine
  • RNA Polymerase II