Figure 5.

CFTR is stabilized only in the ssa1-45 strain at 40°C. CFTR-expressing cells grown exclusively at 26°C or shifted to 40°C for 1 h were harvested at the indicated times after the addition of cycloheximide, and cell extracts were prepared and subjected to immunoblot analysis. (A) Results from a quantitative immunoblot analysis are plotted and the corresponding PhosphorImager analysis is shown. The amount of CFTR at time zero was set to 1. ●, SSA1 cells expressing CFTR at 26°C; ○, ssa1- expressing CFTR at 26°C; ▪, SSA1-expressing CFTR at 40°C; □, ssa1-45 cells expressing CFTR at 40°C. Sec61p serves as a loading control. (B) Degradation of HA-CFTR was assayed in wild-type (●), kar2-1 (○), or kar2-133 (▵) yeast as described in A, and the results were analyzed and quantified. (C) HA-CFTR degradation was measured in wild-type (●) or Δcne1 (○) yeast.