The histone variant macroH2A1.1 is recruited to DSBs through a mechanism involving PARP1

► mH2A1 is required for the repair of DSBs. ► mH2A1.1 is recruited to DSBs through a mechanism involving PARP1. ► mH2A1.1 is not incorporated into nucleosomes at DSBs. ► mH2A1 is required for loading of 53BP1 at DSBs.