Cell Signaling Technology

Product Pathways - Cell Cycle / Checkpoint

p57 Kip2 Antibody #2557

Applications Reactivity Sensitivity MW (kDa) Source
W IP IF-IC H Endogenous 57 Rabbit

Applications Key:  W=Western Blotting  IP=Immunoprecipitation  IF-IC=Immunofluorescence (Immunocytochemistry)
Reactivity Key:  H=Human
Species cross-reactivity is determined by western blot. Species enclosed in parentheses are predicted to react based on 100% sequence homology.

Protocols

Specificity / Sensitivity

p57 Kip2 Antibody detects endogenous levels of total p57 Kip2 protein. The antibody does not recognize p27 Kip1.

Source / Purification

Polyclonal antibodies are produced by immunizing animals with a synthetic peptide corresponding to amino acids near the carboxy terminus of human p57 Kip2. Antibodies are purified by protein A and peptide affinity chromatography.

Western Blotting

Western Blotting

Western blot analysis of extracts from HeLa cells, untreated or treated with dexamethasone (50 nM, 16h) alone or with λ phosphatase, using p57 Kip2 Antibody #2557.

IP

IP

Western blot analysis, using a different p57 Kip2 mouse monoclonal antibody, of whole cell lysate from dexamethasone-treated (50 nM, 16h) HeLa cells (lane 1) and of p57 Kip2 immunoprecipitated from the same lysate using p57 Kip2 Antibody #2557 (lane 5). Lanes 2-4 represent controls for the immunoprecipitation experiment, as indicated.

IF-IC

IF-IC

Confocal immunofluorescent analysis of HeLa cells, untreated (left) or dexamethasone-treated (right), using p57 Kip2 Antibody (green). Actin filaments were labeled with DY-554 phalloidin (red). Blue pseudocolor = DRAQ5® #4084 (fluorescent DNA dye).


Background

p27 Kip1 is a member of the Cip/Kip family of cyclin-dependent kinase inhibitors. Like its relatives, p57 Kip2 and p21 Waf1/Cip1, the ability to enforce the G1 restriction point is derived from its inhibitory binding to CDK2/cyclin E and other CDK/cyclin complexes. Expression levels of p27 are upregulated in quiescent cells and in cells treated with cAMP or other negative cell cycle regulators. Downregulation of p27 can be induced by treatment with interleukin-2 or other mitogens; this involves phosphorylation of p27 and its degradation by the ubiquitin-proteasome pathway (1-4).

p57 Kip2 (Cyclin-dependent kinase inhibitor 1C) functions as a tumor suppressor. Mutations of p57 Kip2 have been associated with numerous human malignancies as well as Beckwith–Wiedemann syndrome (BWS), characterized by an increased risk of childhood cancer. The amino-terminal CDK inhibitory domain, common to the family, binds to and inhibits CDK/cyclin complexes and restricts cell cycle progression (5). The unique central region of p57 Kip2 interactes with LIMK-1, a downstream effector of the Rho family of GTPases. By sequestering LIMK-1 in the nucleus, p57 Kip2 disrupts actin dynamics within cells and may be linked to its essential role in embryonic development (6). In addition, the carboxyl-terminal QT domain of p57KIP2 binds to and inhibits JNK/SAPK activity regulating cellular apoptosis and differentiation (7). Expression levels of human p57 Kip2 are more restricted then other CDK inhibitors (8) and are controlled by ubiquitination/degradation via the Skp1/Cul1/F-box-type E3 ubiquitin ligase complex SCF-Skp2. This effect is dependent on Thr310 (9). A similar threonine phosphorylation site in p27 Kip1, Thr187, has also been shown to regulate protein stability (10).

  1. Lloyd, R.V. et al. (1999) Am. J. Pathol. 154, 313-323.
  2. Polyak, K. et al. (1994) Genes Dev. 8, 9-22.
  3. Kato, J.Y. et al. (1994) Cell 79, 487-496.
  4. Vlach, J. et al. (1997) EMBO J. 16, 5334-5344.
  5. Pateras, I.S. et al. (2009) Mol Cancer Res 7, 1902-19.
  6. Yokoo, T. et al. (2003) J Biol Chem 278, 52919-23.
  7. Chang, T.S. et al. (2003) J Biol Chem 278, 48092-8.
  8. Lee, M.H. et al. (1995) Genes Dev 9, 639-49.
  9. Kamura, T. et al. (2003) Proc Natl Acad Sci U S A 100, 10231-6.
  10. Ishida, N. et al. (2000) J Biol Chem 275, 25146-54.

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

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