Figure 5.
Folding stressors cause aggregation and result in failure to target aggregation-prone substrates to the proteasome. (A) Measurements of fold degron stability (top: Cyto-Deg, middle: ERm-Deg) and fold PSR activity (bottom) in titrations of bortezomib, canavanine, or AZC for cells expressing an empty vector (solid) or a copy of HSF1Δ1-147 (dotted). Significance was collectively tested across the three highest concentrations measured by combining data from these concentrations into one group per genetic context, then performing a paired two-sided Student’s t test. Error bars denote standard error for n ≥ 3 biological replicates. (B and C) Fluorescent localization of ERm-Deg (GFP), Cyto-Deg (GFP), or Hsp104-mKate2 (RFP) in cells treated with 800 µM canavanine, 4 mM AZC, 40 µM bortezomib, or no treatment for 5 h. Cells are outlined in yellow dashed lines. ns, P > 0.05; **, P < 0.01; and ***, P < 0.001. btz, bortezomib; can, canavanine.