Figure 6. USP3 deubiquitinates at K13–15 and K118–119 on γH2AX. HeLa cells were transfected with the indicated FLAG-H2AX constructs in combination with either Myc-USP3 or empty control vector, and processed similar to that described in Figure 5. The eluates of FLAG gel retained immunoprecipitates were immunoblotting analyzed with anti-FLAG and γH2AX antibodies. (A) HeLa cells transfected with constructs for FLAG-tagged WT H2AX. (B) HeLa cells transfected with constructs for FLAG-tagged H2AX with K118–119R. (C) HeLa cells transfected with constructs for FLAG-tagged H2AX with K13–15R. The images were heavily exposed necessarily to show mono-Ub-γH2AX species.