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. Author manuscript; available in PMC: 2021 Nov 1.
Published in final edited form as: DNA Repair (Amst). 2020 Aug 11;95:102948. doi: 10.1016/j.dnarep.2020.102948

Figure 1. MDC1 is a scaffold protein which propagates the phosphorylation of H2AX to form γ-H2AX.

Figure 1.

A. DNA double-stranded breaks form free DNA ends. B. Free DNA ends are detected by the MRN complex, which recruits ATM kinase to phosphorylate H2AX to form γ-H2AX. C. MDC1 interacts directly with γ-H2AX to recruit additional MRN complex and ATM, amplifying the γ-H2AX signal. It also recruits RNF8, resulting in the ubiquitination of γ-H2AX. D. In the absence of MDC1, free ends are still detected by the MRN complex, but the γ-H2AX signal is not propagated onto nearby chromatin to form visible γ-H2AX foci.