Involved in DNA double-strand break repair (DSBR). The Rad50/Mre11 complex possesses single-strand endonuclease activity and ATP-dependent double-strand-specific 3'-5' exonuclease activity. Rad50 provides an ATP-dependent control of Mre11 by unwinding and/or repositioning DNA ends into the Mre11 active site (By similarity). Binds 1 zinc ion per homodimer. Homodimer. Forms a complex with Mre11 (By similarity). The two conserved Cys that bind zinc constitute the zinc-hook, which separates the large intramolecular coiled coil regions. The 2 Cys residues coordinate one molecule of zinc with the help of the 2 Cys residues of the zinc-hook of another Rad50 molecule, thereby forming a V-shaped homodimer (By similarity). Belongs to the SMC family. RAD50 subfamily.