FIGURE 9.

ERp29 depletion impedes WT-CFTR maturation. CFBE41o− WT bronchial epithelial cells that overexpressed WT-CFTR were transfected with control (non-target) or ERp29-specific siRNA as described under “Experimental Procedures.” After 48 h, cells were pulse-labeled with [³⁵S]Met/Cys and chased in the presence of excess unlabeled Met/Cys. Cells were lysed at the indicated times of chase, and CFTR was recovered from equal amounts of whole-cell lysate protein by immunoprecipitation using monoclonal anti-CFTR (clone 3G11). Immunoprecipitated CFTR was detected by SDS-PAGE and fluorography. A, representative fluorograms (equal time exposure; n = 4 independent experiments). Arrows B and C depict immature and mature CFTR as described in the text. B, relative expression of CFTR B form in CFBE41o− WT in cells transfected with control siRNA (gray bars) or ERp29 siRNA (open bars) was quantified by densitometry of n = 4 independent experiments after 0 and 1 h of chase. Data (mean ± S.E.) were normalized to values in control siRNA-transfected cells at t = 0.