期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 275, 期 44, 页码 34710-34718出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M005179200
关键词
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DNA. topoisomerase II alpha is required for chromatin condensation during prophase, This process is temporally linked with the appearance of mitosis-specific phosphorylation sites on topoisomerase II alpha including one recognized by the MPM-2 monoclonal antibody. We now report that the ability of mitotic extracts to create the MPM-2 epitope on human topoisomerase II alpha is abolished by immunodepletion of protein kinase CK2. Furthermore, the MPM-2 phosphoepitope on topoisomerase II alpha can be generated by purified CR2. Phosphorylation of C-truncated topoisomerase II alpha mutant proteins conclusively shows, that the MPM-2 epitope is present in the last 163 amino acids. Use of peptides containing all conserved CK2 consensus sites in this region indicates that only the peptide containing Arg-1466 to Ala-1485 is able to compete with topoisomerase II alpha for binding of the MPM-2 antibody. Replacement of Ser-1469 with Ala abolishes the ability of the phosphorylated peptide to bind to the MPM-2 antibody while a peptide containing phosphorylated Ser-1469 binds tightly. Surprisingly, the MPM-2 phosphoepitope influences neither the catalytic activity of topoisomerase II alpha nor its, ability to form molecular complexes with CR2 in vitro. In conclusion, we have identified protein kinase CR2 as a new MPM-2 kinase able to phosphorylate an important mitotic protein, topoisomerase II alpha; on Ser-1469.
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