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DNA-PKcs Function Regulated Specifically by Protein Phosphatase 5
Thomas Wechsler, Benjamin P. C. Chen, Ryan Harper, Keiko Morotomi-Yano, Betty C. B. Huang, Katheryn Meek, James E. Cleaver, David J. Chen and Matthias Wabl
Proceedings of the National Academy of Sciences of the United States of America
Vol. 101, No. 5 (Feb. 3, 2004), pp. 1247-1252
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/3148820
Page Count: 6
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Unrepaired DNA double-strand breaks can lead to apoptosis or tumorigenesis. In mammals double-strand breaks are repaired mainly by nonhomologous end-joining mediated by the DNA-PK complex. The core protein of this complex, DNA-PKcs, is a DNA-dependent serine/threonine kinase that phosphorylates protein targets as well as itself. Although the (auto)phosphorylation activity has been shown to be essential for repair of both random double-strand breaks and induced breaks at the immunoglobulin locus, the corresponding phosphatase has been elusive. In fact, to date, none of the putative phosphatases in DNA double-strand break repair has been identified. Here we show that protein phosphatase 5 interacts with DNA-PKcs and dephosphorylates with surprising specificity at least two functional sites. Cells with either hypo- or hyperphosphorylation of DNA-PKcs at these sites show increased radiation sensitivity.
Proceedings of the National Academy of Sciences of the United States of America © 2004 National Academy of Sciences