DOI: 10.1126/science.281.5383.1677 ISSN:

Activation of the ATM Kinase by Ionizing Radiation and Phosphorylation of p53

Christine E. Canman, Dae-Sik Lim, Karlene A. Cimprich, Yoichi Taya, Katsuyuki Tamai, Kazuyasu Sakaguchi, Ettore Appella, Michael B. Kastan, Janet D. Siliciano
  • Multidisciplinary

The p53 tumor suppressor protein is activated and phosphorylated on serine-15 in response to various DNA damaging agents. The gene product mutated in ataxia telangiectasia, ATM, acts upstream of p53 in a signal transduction pathway initiated by ionizing radiation. Immunoprecipitated ATM had intrinsic protein kinase activity and phosphorylated p53 on serine-15 in a manganese-dependent manner. Ionizing radiation, but not ultraviolet radiation, rapidly enhanced this p53-directed kinase activity of endogenous ATM. These observations, along with the fact that phosphorylation of p53 on serine-15 in response to ionizing radiation is reduced in ataxia telangiectasia cells, suggest that ATM is a protein kinase that phosphorylates p53 in vivo.

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