Stability of checkpoint kinase 2 is regulated via phosphorylation at serine 456

J Biol Chem. 2007 Oct 12;282(41):30311-21. doi: 10.1074/jbc.M704642200. Epub 2007 Aug 21.


Checkpoint kinase 2 (Chk2), a DNA damage-activated protein kinase, is phosphorylated at Thr-68 by ataxia telangiectasia mutated leading to its activation by phosphorylation at several additional sites. Using mass spectrometry we identified a new Chk2 phosphorylation site at Ser-456. We show that phosphorylation of Ser-456 plays a role in the regulation of Chk2 stability particularly after DNA damage. Mutation of Ser-456 to alanine results in hyperubiquitination of Chk2 and dramatically reduced Chk2 stability. Furthermore, cells expressing S456A Chk2 show a reduction in the apoptotic response to DNA damage. These findings suggest a mechanism for stabilization of Chk2 in response to DNA damage via phosphorylation at Ser-456 and proteasome-dependent turnover of Chk2 protein via dephosphorylation of the same residue.

MeSH terms

  • Amino Acid Sequence
  • Apoptosis
  • Cell Line, Tumor
  • Cell Separation
  • Checkpoint Kinase 2
  • DNA Damage
  • Flow Cytometry
  • Humans
  • Mass Spectrometry
  • Molecular Conformation
  • Molecular Sequence Data
  • Mutation
  • Phosphorylation
  • Proteasome Endopeptidase Complex / metabolism
  • Protein Structure, Tertiary
  • Protein-Serine-Threonine Kinases / chemistry*
  • Serine / chemistry*


  • Serine
  • Checkpoint Kinase 2
  • CHEK2 protein, human
  • Protein-Serine-Threonine Kinases
  • Proteasome Endopeptidase Complex