Christian Münch, group leader at the IBC2, contributed to a study recently published in Nature. The work was led by Dipanjan Chowdhury at the Dana-Farber/Harvard Cancer Center and described the role of an uncharacterized protein – TIRR – in regulating DNA double-strand repair. TIRR binds to the tandem Tudor domain of 53BP1, a protein important for DNA double-strand repair, masking the histone methyl-lysine binding motif on 53BP1 and preventing chromatin binding. Also, TIRR stabilizes the nuclear-soluble 53BP1 fraction through direct binding. Through these mechanisms, TIRR affects 53BP1 activity and DNA double-strand repair efficiency.