CHD4 interacts with the DNA damage response kinase ATM. (A) A schematic representation of the CHD4 protein, NLS; the putative nuclear localisation signal, PHD; plant homeodomain, Chromo; chromodomain, helicase and ATPase domain region. (B, C) ATM proficient C3ABR cells either mock irradiated or irradiated with 6Gy IR, 1hr after IR cell lysates were prepared and immunoprecipitated with for ATM, CHD4 or mock (IgG). The indicated proteins were subjected to western blot analysis. (D) Cell lysates prepared from C3ABR cells were subjected to pulldown assays using purified GST-CHD4 fusion protein fragments spanning the full length of CHD4. Upper Panel: ATM western blot of GST-CHD4 fusion fragment pulldown. Lower Panel: Coomassie stain of GST-CHD4 fusion fragments following SDS-PAGE. (E) ATM western blot following a GST-CHD4 fragment 7 pulldown or GST alone (NS) pulldown from L3 (ATM deficient) or C3ABR (ATM proficient) cell lysates.