title: Identification of CGI-121, a novel PRPK (p53-related protein kinase)-binding protein.
abstract: 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.
authors.affiliation: First Department of Pathology, Ehime University School of Medicine, Shitsukawa, Shigenobucho, Onsengun, Ehime 791-0295, Japan.
authors.forename: Akifumi
authors.initials: A
authors.lastname: Miyoshi
authors.forename: Katsumi
authors.initials: K
authors.lastname: Kito
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Aramoto
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Abe
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Norifumi
authors.initials: N
authors.lastname: Ueda
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis; D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D003001:Cloning, Molecular; D020224:Expressed Sequence Tags; D014644:Genetic Variation; D018922:HL-60 Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D013737:Testis / Q000201:enzymology; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D018797:Cell Cycle Proteins; D047908:Intracellular Signaling Peptides and Proteins; D011994:Recombinant Proteins; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; C441644:TP53RK protein, human