Extended Data Fig. 3: Comparing the structure of Ku among the LR synaptic complex, the SR synaptic complex and previously published models.

a, Ku structure in the LR complex showing outward rotations of both Ku70 and Ku80 vWA domains. b, Crystal structure of the XLF Ku-binding motif (KBM) bound to Ku showing the outward rotation of only the Ku80 vWA domain²⁹. c, Crystal structure of apo Ku showing no rotation of either Ku70 or Ku80 vWA domains²². d, Conformation of Ku shown in the cryo-EM structure of the apo DNA-PK complex³⁰. The Ku70 vWA domain is rotated outward, triggered by binding of DNA-PKcs. e, f, Two copies of the XLF Ku-binding motif bound to Ku in the SR complex. The conformation of both copies is the same as the one in the LR complex (a), despite the fact that DNA-PKcs is not present. Colour codes for Ku70 and Ku80 are the same as in Fig. 1.