Formation of alternative proteasomes: Same lady, different cap?

► The Hb-Y-X motif is conserved in many eukaryotic Cdc48/p97 complexes. ► Both the p97 and CSN complexes show architectural paralogy to the 19S proteasome. ► The CSN complex binds p97 and could potentially form a 19S-like cap. ► We hypothesize that p97/CSN forms a promiscuous proteasome activator.