FIGURE 3.

The UPS slows prior to SOD1^A4V aggregation. (A) Under normal conditions, mcherry^CL1 is rapidly degraded by the proteasome, but if the UPS is overwhelmed or impaired, we see an accumulation of mcherry^CL1 which can be measured by an increase in fluorescence intensity. The fluorescence intensity of SOD1^A4V-GFP and mcherry^CL1 was followed in NSC-34 cells expressing (B) soluble SOD1^A4V-GFP and (C) insoluble SOD1^A4V-GFP. Data represent individual cell traces with arrows indicating the time point at which insoluble SOD1^A4V–GFP aggregates first appear.