Ubiquitin tagging controls protein fate, but how the COP1-DET1 E3 ligase works was unclear. Here, the authors present cryo-EM structures of an inactive stacked assembly that switches to an active dimer on substrate binding, with DET1 guiding enzymes to start and co-workers to extend ubiquitin chains.
- Shan Wang
- Fei Teng
- Ming-Yuan Su