Identification of novel substrates for human checkpoint kinase Chk1 and Chk2 through genome-wide screening using a consensus Chk phosphorylation motif

Exp Mol Med. 2007 Apr 30;39(2):205-12. doi: 10.1038/emm.2007.23.


Checkpoint kinase 1 (Chk1) and Chk2 are effector kinases in the cellular DNA damage response and impairment of their function is closely related to tumorigenesis. Previous studies revealed several substrate proteins of Chk1 and Chk2, but identification of additional targets is still important in order to understand their tumor suppressor functions. In this study, we screened novel substrates for Chk1 and Chk2 using substrate target motifs determined previously by an oriented peptide library approach. The potential candidates were selected by genome-wide peptide database searches and were examined by in vitro kinase assays. ST5, HDAC5, PGC-1alpha, PP2A PR130, FANCG, GATA3, cyclin G, Rad51D and MAD1a were newly identified as in vitro substrates for Chk1 and/or Chk2. Among these, HDAC5 and PGC-1a were further analyzed to substantiate the screening results. Immunoprecipitation kinase assay of full-length proteins and site-directed mutagenesis analysis of the target motifs demonstrated that HDAC5 and PGC-1alpha were specific targets for Chk1 and/or Chk2 at least in vitro.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Checkpoint Kinase 1
  • Checkpoint Kinase 2
  • Consensus Sequence*
  • Genome, Human / genetics*
  • Heat-Shock Proteins / chemistry
  • Heat-Shock Proteins / metabolism
  • Histone Deacetylases / chemistry
  • Histone Deacetylases / metabolism
  • Humans
  • Molecular Sequence Data
  • Peptide Fragments / chemistry
  • Peptide Fragments / metabolism
  • Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha
  • Phosphorylation
  • Phosphoserine / metabolism
  • Protein Kinases / metabolism*
  • Protein-Serine-Threonine Kinases / metabolism*
  • Substrate Specificity
  • Transcription Factors / chemistry
  • Transcription Factors / metabolism


  • Heat-Shock Proteins
  • PPARGC1A protein, human
  • Peptide Fragments
  • Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha
  • Transcription Factors
  • Phosphoserine
  • Protein Kinases
  • Checkpoint Kinase 2
  • CHEK1 protein, human
  • CHEK2 protein, human
  • Checkpoint Kinase 1
  • Protein-Serine-Threonine Kinases
  • HDAC5 protein, human
  • Histone Deacetylases