Rad50 can dimerize both through its head domain and through a zinc-binding dimerization motif at the opposite end of the coiled-coil known as the “zinc-hook”.[7] Results from atomic force microscopy suggest that in free Mre11-Rad50-Nbs1 complexes, the zinc-hooks of a single Rad50 dimer associate to form a closed loop, while the zinc-hooks snap apart upon binding DNA, adopting a conformation that is thought to enable zinc-hook-mediated tethering of broken DNA ends.[8]