Ubiquitin degradation with its substrate, or as a monomer in a ubiquitination-independent mode, provides clues to proteasome regulation.

ABSTRACT: The mechanisms that regulate the ubiquitin (Ub)-proteasome system's own components, although critically important, are largely unknown. Ub, a principal component of the system, must be maintained at adequate levels to support cellular homeostasis under basal and stressed conditions. It was suggested that Ub is degraded as part of the polyubiquitin chain along with its substrate. Here, we demonstrate in a direct manner that Ub is indeed degraded in a "piggyback" mechanism. Also, it has been shown that monomeric Ub can be rapidly degraded when a C-terminal tail of a minimal length is fused to it. The tail, which may represent the substrate or part of it, or a naturally occurring extended form of Ub, probably allows entry of the protein into the 20S catalytic chamber, while Ub serves as an an

SUBMITTER: Shabek N 

PROVIDER: S-EPMC2715473 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature