Cell Signaling Technology

Product Pathways - Cell Cycle / Checkpoint

Phospho-CDK9 (Thr186) Antibody #2549

Applications Reactivity Sensitivity MW (kDa) Source
W H M R Mk Endogenous 42, 55 Rabbit

Applications Key:  W=Western Blotting
Reactivity Key:  H=Human  M=Mouse  R=Rat  Mk=Monkey
Species cross-reactivity is determined by western blot. Species enclosed in parentheses are predicted to react based on 100% sequence homology.

Protocols

Specificity / Sensitivity

Phospho-CDK9 (Thr186) Antibody detects endogenous levels of CDK9 only when phosphorylated at Thr186. The antibody recognizes both the 42 kDa isoform and the less abundant 55 kDa isoform.

Source / Purification

Polyclonal antibodies are produced by immunizing animals with a synthetic phosphopeptide corresponding to residues surrounding Thr186 of human CDK9. Antibodies are purified using peptide affinity chromatography.

Western Blotting

Western Blotting

Western blot analysis of extracts from various cell types, untreated or treated with λ phosphatase and calf intestinal phosphatase (CIP), using Phospho-CDK9 (Thr186) Antibody (upper) or CDK9 (C12F7) Rabbit mAb #2316 (lower).

Background

P-TEFb is a general transcription factor that regulates transcription elongation through phosphorylation of the C-terminal tail domain (CTD) of RNA polymerase II (RNAP II). The P-TEFb complex composed of a catalytic subunit, CDK9, and its regulatory cyclin partner, which can be cyclin T1, T2a, T2b or K (reviewed in 1,2). P-TEFb is recruited by the HIV Tat protein to allow transcriptional elongation, and subsequent replication of the viral genome. Inhibition of P-TEFb function therefore has potential for HIV therapy.CDK9 exists as two isoforms, an abundant 42 kDa isoform, and a less abundant 55 kDa isoform, which contains an amino-terminal extension (3). The two forms likely have distinct purposes based on differential expression during lymphocyte activation (4,5) and on their localization within the nucleus (5).Cyclin dependent kinases (CDKs) are activated in part by cyclin binding and by phosphorylation of a conserved threonine in the T-loop domain. Phosphorylation of CDK9 at the T-loop Thr186 by an unidentified nuclear kinase may be important in P-TEFb activation (6) and regulation of HIV transcription (7). Acetylation of CDK9 at Lys44 affects its ability to phosphorylate the RNAPII CTD (8).

  1. Rice, A.P. and Herrmann, C.H. (2003) Curr HIV Res 1, 395-404.
  2. De Falco, G. and Giordano, A. Cancer Biol Ther 1, 342-7.
  3. Shore, S.M. et al. (2003) Gene 307, 175-82.
  4. Shore, S.M. et al. (2005) Gene 350, 51-8.
  5. Liu, H. and Herrmann, C.H. (2005) J Cell Physiol 203, 251-60.
  6. Chen, R. et al. (2004) J Biol Chem 279, 4153-60.
  7. Ammosova, T. et al. (2005) Retrovirology 2, 47.
  8. Fu, J. et al. (2007) Mol Cell Biol 27, 4641-51.

Application References

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Companion Products

For Research Use Only. Not For Use In Diagnostic Procedures.

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