Destroying the ring: Freeing DNA from Ku with ubiquitin

► The Ku70-Ku80 heterodimer (Ku) is a critical component of the NHEJ pathway. ► Ku removal from DNA is an important aspect of pre- and post-repair mechanisms. ► Ku80 can be removed from DNA via its K48-linked poly-ubiquitylation. ► Ubiquitylation, followed by protein unfolding, is emerging as a general mechanism for the release of DNA-bound proteins.