Cell Signaling Technology

Product Pathways - DNA Damage

Phospho-Chk1 (Ser280) Antibody #2347

Applications Reactivity Sensitivity MW (kDa) Source
W H Endogenous 56 Rabbit

Applications Key:  W=Western Blotting
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

Phospho-Chk1 (Ser280) Antibody detects endogenous levels of Chk1 only when phosphorylated at serine 280.

Source / Purification

Polyclonal antibodies are produced by immunizing animals with a synthetic phosphopeptide corresponding to residues surrounding Ser280 of human Chk1. Antibodies are purified by protein A and peptide affinity chromatography.

Western Blotting

Western Blotting

Western blot analysis of extracts from HT29 cells, untreated or UV-treated, using Phospho-Chk1 (Ser280) Antibody (upper) or Chk1 Antibody #2345 (lower).

Background

Chk1 kinase acts downstream of ATM/ATR kinase and plays an important role in DNA damage checkpoint control, embryonic development, and tumor suppression (1). Activation of Chk1 involves phosphorylation at Ser317 and Ser345 and occurs in response to blocked DNA replication and certain forms of genotoxic stress (2). While phosphorylation at Ser345 serves to localize Chk1 to the nucleus following checkpoint activation (3), phosphorylation at Ser317 along with site-specific phosphorylation of PTEN allows for re-entry into the cell cycle following stalled DNA replication (4). Chk1 exerts its checkpoint mechanism on the cell cycle, in part, by regulating the cdc25 family of phosphatases. Chk1 phosphorylation of cdc25A targets it for proteolysis and inhibits its activity through 14-3-3 binding (5). Activated Chk1 can inactivate cdc25C via phosphorylation at Ser216, blocking the activation of cdc2 and transition into mitosis (6). Centrosomal Chk1 has been shown to phosphorylate cdc25B and inhibit its activation of CDK1-cyclin B1, thereby abrogating mitotic spindle formation and chromatin condensation (7). Furthermore, Chk1 plays a role in spindle checkpoint function through regulation of aurora B and BubR1 (8). Research studies have implicated Chk1 as a drug target for cancer therapy as its inhibition leads to cell death in many cancer cell lines (9).

Akt has been shown to phosphorylate Chk1 at Ser280 in vitro, and preliminary data suggests that Akt activity may prevent Chk1 activation (5).

  1. Liu, Q. et al. (2000) Genes Dev 14, 1448-59.
  2. Zhao, H. and Piwnica-Worms, H. (2001) Mol Cell Biol 21, 4129-39.
  3. Jiang, K. et al. (2003) J Biol Chem 278, 25207-17.
  4. Martin, S.A. and Ouchi, T. (2008) Mol Cancer Ther 7, 2509-16.
  5. Chen, M.S. et al. (2003) Mol Cell Biol 23, 7488-97.
  6. Zeng, Y. et al. (1998) Nature 395, 507-10.
  7. Löffler, H. et al. (2006) Cell Cycle 5, 2543-7.
  8. Zachos, G. et al. (2007) Dev Cell 12, 247-60.
  9. Garber, K. (2005) J Natl Cancer Inst 97, 1026-8.
  10. Shtivelman, E. et al. (2002) Curr. Biol. 12, 919-924.

Application References

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Companion Products

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

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