Figure 1.

Balance between proteasomal load and capacity. a. Under normal conditions, cells maintain a balance between proteasome load and capacity via modulation of factors such as the protein-synthesis rate, chaperone capacity, deubiquitination activity, and the synthesis and assembly of proteasome subunits. b. Multiple factors can enhance or mitigate the load and capacity of the proteasome, thereby disturbing this balance. If compensatory mechanisms cannot be activated, this disturbance leads to proteotoxic stress and to the activation of apoptotic pathways.