Analyzing ATM Function by Electroporation of Endonucleases and Immunofluorescence Microscopy.

Ataxia-telangiectasia mutated (ATM) protein, which plays a crucial role in DNA damage checkpoint signaling, is activated by DNA double strand breaks (DSBs) caused by ionizing radiation. While radiation exposure induces various types of DNA break ends, here, we describe a method, which enables creating defined types of DSBs by applying restriction endonucleases and foci analysis by immunofluorescence microscopy. The protocol greatly improves our knowledge on specific roles of ATM function in different DNA repair pathways.