DNA is like the computer code of the body, and it must be preserved for our bodies to survive. Yet, as cells grow and change, DNA is vulnerable to defects, especially double strand breaks (DSBs). In fact, DSBs regularly occur throughout one’s lifetime. The DNA is protected, however, by DNA repair machinery. A new study from scientists at Osaka University and The University of Tokyo describes the crystal structure of a crucial part of this machinery, the binding of RNF168 to ubiquitylated proteins and find a unique binding not seen in other ubiquitylated protein interactions.