In vivo interaction of nucleophosmin/B23 and protein C23 during cell cycle progression in HeLa cells.
By using the cross-linking reagent, DSP, efforts were made to identify the protein(s) that interact with nucleophosmin/B23. A cross-linked protein complex at molecular weight of about 140 kDa was recognized by both nucleophosmin/B23 and protein C23 MAbs. Both C23 and nucleophosmin/B23 could be detected from the cross-linked complex immunoprecipitated by C23 MAb. The association between nucleophosmin/B23 and protein C23 while being observed at interphase and cytokinesis, was not detected in prometaphase and metaphase cells. Interactions of nucleophosmin/B23 with C23 not only could be found in cells in which nucleophosmin/B23 and C23 were both mainly localized to the nucleolus, but also in cells in which nucleophosmin/B23 and C23 had translocated from the nucleolus to the nucleoplasm during actinomycin D-induced cell growth inhibition. The purified recombinant GST-B23 being phosphorylated by prometaphase cell extracts (nocodazole-arrested cells) or cdc2 kinase could still be co-immunoprecipitated with C23. Consequently, the fact that nucleophosmin/B23 did not interact with C23 during mitosis could not be explained simply by mitotic phosphorylation of nucleophosmin/B23. Our findings suggest some possibilities for further elucidation of the actions of nucleophosmin/B23 and protein C23 in cell cycle progression and cell growth.
Liu
H T
HT
Department of Pharmacology, College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan.
Yung
B Y
BY
D002453:Cell Cycle; D002466:Cell Nucleolus / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D008938:Mitosis; D009687:Nuclear Proteins / Q000737:chemistry*; D000090243:Nucleophosmin; D010750:Phosphoproteins / Q000737:chemistry*; D010766:Phosphorylation; D016601:RNA-Binding Proteins / Q000737:chemistry*; D000097796:Nucleolin
D009687:Nuclear Proteins; D000090243:Nucleophosmin; D010750:Phosphoproteins; D016601:RNA-Binding Proteins; D000097796:Nucleolin; C000716967:NPM1 protein, human