Component of the MRN complex, which plays a central role in double-strand break (DSB) repair, DNA recombination, maintenance of telomere integrity and meiosis. The complex possesses single-strand endonuclease activity and double-strand-specific 3'-5' exonuclease activity, which are provided by MRE11. RAD50 may be required to bind DNA ends and hold them in close proximity. This could facilitate searches for short or long regions of sequence homology in the recombining DNA templates, and may also stimulate the activity of DNA ligases and/or restrict the nuclease activity of MRE11 to prevent nucleolytic degradation past a given point. The complex may also be required for DNA damage signaling via activation of the ATM kinase. In telomeres the MRN complex may modulate t-loop formation. Interaction with SAMHD1 stimulates the double-strand-specific 3'-5' exonuclease activity. Component of the MRN complex composed of two heterodimers RAD50/MRE11 associated with a single NBN (By similarity). As part of the MRN complex, interacts with MCM9; the interaction recruits the complex to DNA repair sites (By similarity). Component of the BASC complex, at least composed of BRCA1, MSH2, MSH6, MLH1, ATM, BLM, RAD50, MRE11 and NBN (By similarity). Found in a complex with TERF2 (By similarity). Interacts with DCLRE1C/Artemis and DCLRE1B/Apollo (By similarity). Interacts with ATF2 (By similarity). Interacts with EXD2 (By similarity). Interacts with MRNIP (By similarity). Interacts with SAMHD1; leading to stimulate 3'-5' exonuclease activity (By similarity). Interacts (when ubiquitinated) with UBQLN4 (via its UBA domain) (By similarity). Interacts with CYREN (via XLF motif) (PubMed:30017584). Localizes to discrete nuclear foci after treatment with genotoxic agents. Ubiquitinated following DNA damage. Ubiquitination triggers interaction with UBQLN4, leading to MRE11 removal from chromatin and degradation by the proteasome. Belongs to the MRE11/RAD32 family.