Figure 5. USP3 deubiquitinates at K13–15 on H2A in response to DNA damage. HeLa cells transfected with indicated FLAG-tagged WT or mutant H2A constructs in combination with either Myc-USP3 or control vector and, were UV irradiated. The lysates from transfected cells were prepared and directly used for western blotting shown as input. Alternatively, the lysates were processed for anti-FLAG immunoprecipitates as described in the “Materials and Methods” section. The eluates of FLAG gel retained immunoprecipitates were analyzed by immunoblotting with anti-FLAG or uH2A antibodies. (A) HeLa cells transfected with constructs for FLAG-tagged WT H2A. (B) HeLa cells transfected with constructs for FLAG-tagged H2A with K118 to 119R. (C) HeLa cells transfected with constructs for FLAG-tagged H2A with K13 to 15R.