Ubiquitinating a phosphorylated Cdk inhibitor on the blades of the Cdc4 beta-propeller

Abstract

Substrate binding by the SCFCdc4 ubiquitin ligase is regulated by phosphorylation. In this issue of Cell, Orlicky et al. describe the crystal structure of the Cdc4 subunit bound to a high-affinity substrate phosphopeptide. This structure provides insights into the binding interaction and how a precise mechanism involving multiple regulatory phosphorylations may be mediated by a single binding site.