Identification of CGI-121, a novel PRPK (p53-related protein kinase)-binding protein

Biochem Biophys Res Commun. 2003 Apr 4;303(2):399-405. doi: 10.1016/s0006-291x(03)00333-4.


PRPK (p53-related protein kinase) has been reported as a novel protein kinase which binds to the tumor suppressor protein p53 and induces phosphorylation of p53 at Ser 15. To identify novel binding partners of PRPK, we performed a yeast two-hybrid screening and isolated an expressed sequence tag CGI-121 by which a 20-kDa protein was encoded. We demonstrated the protein-protein interaction of CGI-121 with PRPK in vivo and in vitro. The protein expression of CGI-121 was observed in many cell lines and was immunocytochemically identified in both the nucleus and cytosol. Although PRPK interacted with both CGI-121 and p53, several attempts to demonstrate an association between CGI-121 and p53 were unsuccessful. In addition, coprecipitation of p53 using recombinant PRPK was inhibited by adding recombinant CGI-121 in vitro, suggesting that CGI-121 could act as a potent inhibitor of the binding of PRPK to p53.

MeSH terms

  • Amino Acid Sequence
  • Apoptosis
  • Base Sequence
  • Cell Cycle Proteins / chemistry
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • Cell Line
  • Cloning, Molecular
  • Expressed Sequence Tags
  • Genetic Variation
  • HL-60 Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins
  • Male
  • Molecular Sequence Data
  • Molecular Weight
  • Protein Kinases / chemistry
  • Protein Kinases / genetics
  • Protein Kinases / metabolism*
  • Protein Serine-Threonine Kinases
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Saccharomyces cerevisiae / enzymology
  • Saccharomyces cerevisiae / genetics
  • Testis / enzymology
  • Transcription, Genetic
  • Transfection


  • Cell Cycle Proteins
  • Intracellular Signaling Peptides and Proteins
  • Recombinant Proteins
  • Protein Kinases
  • Protein Serine-Threonine Kinases
  • TP53RK protein, human

Associated data

  • GENBANK/AY157986
  • GENBANK/AY157987