The Extent of Extended-Ubiquitin Binding to the Proteasome.

In this issue of Structure, Lu et al. (2020) describe an NMR-based study showing the proteasome ubiquitin receptor hRpn13 bound to an extended conformation of K48-diubiquitin that is different from previously described structures of K48-diubiquitin. Observed dynamic binding properties suggest an ability of substrates to hop between proteasome ubiquitin receptors.