Mechanisms controlling CDK9 activity

Front Biosci. 2006 Sep 1;11:2598-613. doi: 10.2741/1994.


This review primarily focuses on the mechanisms that modulate CDK9 activity and its recruitment to cellular genes, where it phosphorylates the C-terminal domain of RNA polymerase II (RNAPII) as well as negative elongation factors. CDK9 associates with each of four cyclins (T1, T2a, T2b and K), forming distinct positive transcription elongation factors (P-TEFb). Research done during the past decade has demonstrated a role for P-TEFb in stimulating elongation of otherwise paused RNAPII transcripts. Recent work suggests that P-TEFb also positively modulates other steps during transcription. In addition, "abnormal" CDK9 function is associated with certain diseases. Specifically, the activity of the cyclin T1/CDK9 complex is essential for HIV-1 replication and CDK9 upregulation is associated with cardiac hypertrophy. Thus, the role of CDK9 in these processes, and the possibility of therapeutically targeting CDK9, will also be briefly discussed.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Review

MeSH terms

  • Cell Cycle Proteins
  • Cyclin-Dependent Kinase 9 / metabolism*
  • Cyclins / metabolism
  • Lymphocyte Activation
  • Macromolecular Substances
  • Nuclear Proteins
  • Oncogene Proteins, Fusion / physiology
  • Phosphorylation
  • Positive Transcriptional Elongation Factor B / physiology
  • RNA / metabolism
  • RNA Polymerase II
  • T-Lymphocytes
  • Transcription Factors
  • Transcription, Genetic*


  • BRD4 protein, human
  • Cell Cycle Proteins
  • Cyclins
  • Macromolecular Substances
  • Nuclear Proteins
  • Oncogene Proteins, Fusion
  • Transcription Factors
  • RNA
  • Positive Transcriptional Elongation Factor B
  • Cyclin-Dependent Kinase 9
  • RNA Polymerase II