DNA double strand breaks (DSB) in mammalian cells result in the activation of the ATM protein kinase. This leads to phosphorylation of numerous downstream transducer and effector proteins that coordinate a cellular response including DNA repair, cell cycle arrest or apoptosis. We have developed a reporter protein that allows the measurement of ATM kinase activity in single living cells. This CFP-YFP FRET-based biosensor uses an ATM phosphorylation site and an FHA phosphospecific binding domain to produce a phosphorylation-induced change in conformation, which alters the FRET efficiency between CFP and YFP. We show that the reporter provides a measurable output in response to DSBs and is specific for ATM over ATR or DNA-PK. We expect the description of the spatiotemporal dynamics of ATM activity in living cells that this reporter provides will be helpful in providing a more detailed understanding of the DNA damage response.

Original languageEnglish
Pages (from-to)1277-1284
Number of pages8
JournalDNA Repair
Issue number9
StatePublished - Sep 1 2007


  • ATM
  • Biosensor
  • FRET
  • Reporter


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