 An improved and comprehensive understanding of the pathophysiology of the proteasome should lead to clinical applications in the future.The proteasomes form a pivotal component for the ubiquitin–proteasome system (UPS)  and corresponding cellular Protein Quality Control (PQC).Protein ubiquitination and subsequent proteolysis and degradation by the proteasome are important mechanisms in the regulation of the cell cycle, cell growth and differentiation, gene transcription, signal transduction and apoptosis.