ThePCIComplexes and the Ubiquitin Proteasome System (UPS) in Plant Development

Abstract

Since the discovery of the ubiquitin proteasome system (UPS) in the 1970s, the UPS field has advanced remarkably, culminating in the 2004 Nobel Prize in Chemistry. The idea that energy should be invested to degrade a substrate, whose own synthesis consumed energy in the first place, was revolutionary (Hershko and Tomkins, 1971). InArabidopsis, ~1400 genes encode components of the UPS, constituting approximately 5% of theArabidopsisproteome (Smalle and Vierstra, 2004), eluding to the great complexity of the UPS system. Describing this complexity is daunting and very much a matter of perspective. This chapter will discuss the UPS in plant development from the point of view of the PCI (Proteasome,CSN, eIF3) or “ZOMES” complexes: the 26S proteasome lid, Cop9 signalosome (CSN), and eIF3 (eukaryote initiation factor 3), and in particular from the point of view of the CSN.