Establishment of a Cell-Free System to Study the Activation of Chk2

The checkpoint kinase Chk2 is activated in response to DNA damage through pathways requiring protein kinases ATM and/or ATR. The means by which Chk2 is activated by these kinases still remains to be addressed. Here we describe a cell-free system to study the activation of Chk2. Chk2 produced by a wheat germ extract in vitro transcription/translation system is inactive and can be activated by incubating with a rabbit reticulocyte lysate. This method will be useful for identification of cofactors required for activation of Chk2.