Many jobs for one good cop - The COP9 signalosome guards development and defense

► The COP9 signalosome (CSN) is a component of the ubiquitin-proteasome system. ► The CSN regulates CULLIN-based E3 ubiquitin ligases (CRLs). ► The CSN is required for proper plant development. ► The CSN is required for effective plant defenses. ► The coordination of CRL-CSN interactions is highly complex.