Figure 4.

CFTR degradation in yeast is compromised in strains defective for proteasome function and ubiquitin conjugation. CFTR-expressing cells grown at 26°C and then incubated for 1 h at 40°C were harvested at the indicated time points after the addition of cycloheximide, and cell extracts were prepared and subjected to SDS-PAGE and immunoblot analysis as described in MATERIALS AND METHODS. Results from a quantitative immunoblot analysis are shown. The amount of CFTR at time zero was set to 1. ●, PRE1PRE2; ○, pre1-1pre2-2; ▪, UBC6UBC7; □, ubc6ubc7.