Abolishment of the interaction between cyclin-dependent kinase 2 and Cdk-associated protein phosphatase by a truncated KAP mutant.
The cyclin-dependent kinase (Cdk)-associated protein phosphatase (KAP) is a human dual-specificity protein phosphatase that dephosphorylates Cdk2 on a conserved threonine residue, T160, in a cyclin dependent manner. Several aberrant KAP transcripts with characteristic deletion regions have been identified in hepatocellular carcinoma tissues. In this report, we demonstrated that multiple aberrant KAP transcripts were also present in a hepatoblastoma cell line (HepG2), albeit harboring a totally different set of deletions. By performing yeast two-hybrid and co-immunoprecipitation experiments, a KAP-Cdk2 interaction domain located in the amino acid 1-34 region was identified. This interaction domain was different from the major protein interface deduced from crystal structure analysis. Using a yeast three-hybrid system, it was shown that the presence of a truncated KAP mutant encoding this interaction domain abolished the wild-type KAP-Cdk2 interaction. In conclusion, a previously unidentified KAP-Cdk2 interaction domain was discovered. Truncated KAP mutants containing this domain interfered with the wild-type KAP-Cdk2 interaction.
Yeh
Chau-Ting
CT
Liver Research Unit, Chang Gung Memorial Hospital, Chang Gung University School of Medicine, 199, Tung Hwa North Road, Taipei 105, Taiwan. catyeh@ms14.hinet.net
Lu
Su-Chuan
SC
Chao
Chung-Hao
CH
Chao
Mei-Ling
ML
D000595:Amino Acid Sequence; D001665:Binding Sites; D042846:CDC2-CDC28 Kinases; D018797:Cell Cycle Proteins; D051357:Cyclin-Dependent Kinase 2; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D054637:Dual-Specificity Phosphatases; D018197:Hepatoblastoma / Q000201:enzymology; D006801:Humans; D008113:Liver Neoplasms / Q000201:enzymology; D011233:Precipitin Tests; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D020798:Two-Hybrid System Techniques
D018797:Cell Cycle Proteins; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; C084429:CDKN3 protein, human; D054637:Dual-Specificity Phosphatases; D017027:Protein Tyrosine Phosphatases