RNA polymerase II transcription elongation and Pol II CTD Ser2 phosphorylation: A tail of two kinases

Nucleus. May-Jun 2014;5(3):224-36. doi: 10.4161/nucl.29347. Epub 2014 May 30.


The transition between initiation and productive elongation during RNA Polymerase II (Pol II) transcription is a well-appreciated point of regulation across many eukaryotes. Elongating Pol II is modified by phosphorylation of serine 2 (Ser2) on its carboxy terminal domain (CTD) by two kinases, Bur1/Ctk1 in yeast and Cdk9/Cdk12 in metazoans. Here, we discuss the roles and regulation of these kinases and their relationship to Pol II elongation control, and focus on recent data from work in C. elegans that point out gaps in our current understand of transcription elongation.

Keywords: Bur1; C. elegans; Cdk12; Cdk9; Ctk1; P-TEFb; RNA Polymerase II; Serine 2; elongation; transcription.

Publication types

  • Review

MeSH terms

  • Animals
  • Cyclin-Dependent Kinase 9 / metabolism*
  • Cyclin-Dependent Kinases / metabolism*
  • Humans
  • Phosphorylation / genetics*
  • RNA Polymerase II / metabolism*
  • Serine / metabolism*
  • Transcription, Genetic / genetics*


  • Serine
  • Cyclin-Dependent Kinase 9
  • Cyclin-Dependent Kinases
  • RNA Polymerase II