Ishan Deshpande and his colleagues from the group of Susan Gasser and the Protein Structure Facility at the FMI elucidated the mechanism of how Mec1-Ddc2, a tumor suppressor involved in DNA damage response assembles at sites of DNA damage. They focus on the Ddc2-RPA interaction, which brings the Mec1-Ddc2 kinase complex to single-stranded DNA at sites of DNA damage. With their structural data, the FMI scientists provide the missing link between two previously published structures, allowing them to assemble a to-scale composite structural model of Mec1-Ddc2 on ssDNA-RPA at DNA damage sites.