 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.Subsequently, a compromised proteasome complex assembly and function lead to reduced proteolytic activities and the accumulation of damaged or misfolded protein species.