Fig. 2
From: MRE11-RAD50-NBS1 complex alterations and DNA damage response: implications for cancer treatment
DNA binding and processing function of MRN complex. a-b Vertical view of MRE11 complex holding synaptic DNA complex (a) and branched DNA (b). Two MRE11 subunits are oriented symmetrically and bind the synaptic DNA complex which is normally seen in HR (a). In collapsed replication fork, branched DNA is hold in MRE11 complex asymmetrically in one half of the MRE11 dimeric cleft (b). c-d Models for MRN complex in processing DNA ends. For initiation of HR, MRN complex binds sister chromatid with broken DNA through a tail-to-tail link with another MRN complex and prepares for the further procedure of HR (c). In NHEJ, two MRN complexes bind the two ends of broken DNA separately. Later, through structure transition, MRN complexes tether and align broken ends for subsequent repair steps (d)