Fig. 1

G1208D-CFTR has defect in protein maturation and shows impaired chloride channel function. a A representative blot showing the expression level and maturation status of G1208-CFTR, WT-CFTR, F508del-CFTR, or vector transiently expressed in HEK293 cells. Band C denotes a mature form of CFTR and Band B denotes an immature form of CFTR. b G1208D-CFTR has defect in protein maturation, with a mean maturation efficiency of 57 %. The data (density of the bands) were quantified from blots as represented in (a) using Image J software and presented as ratio of Band C to Band B (left panel) and ratio of Band C to total protein (B and C + B and B; right panel). The maturation efficiency was defined as the ratio of the mature form CFTR (density of Band C) to the total CFTR protein (density of B and C plus Band B). *P <0.05, n = 3. c The total CFTR protein expression levels of G1208D-CFTR and WT-CFTR are comparable. The densities of the bands were normalized to their loading control, β-actin, respectively. ns: not significant. n = 3. d Representative iodide efflux traces of G1208D-CFTR, WT-CFTR, or vector transiently expressed in HEK293 cells. PKA activating agonists (10 μM forskolin, 100 μM IBMX, and 200 μM cpt-cAMP) were added to activate CFTR channel function. e The maximal iodide efflux rate of G1208D-CFTR is 33 % of that of WT-CFTR. The data were quantified from experiments as represented in (d) and normalized to the total protein concentrations of cell lysates for each sample, respectively. *P <0.05, n = 5. f The levels of CFTR mRNA are similar between WT and G1208D. ns: not significant. n = 9