FIGURE 3.

The half-life of complex-glycosylated ferret WT-CFTR is elevated relative to its human ortholog in HT1080 cells. A, metabolic [³⁵S]methionine pulse-chase experiments were performed on HT1080 cells transiently expressing HA-tagged ferret and human WT-CFTR to evaluate the rates of protein synthesis, processing, maturation, and stability. Top and bottom panels are representative autoradiographs for ferret and human WT-CFTR, respectively. B, shown is quantification of the average intensity of band B at 0 h (Band B₀) for ferret and human CFTR normalized to total protein. C, shown is quantification of the disappearance of band B (lower graph) over the course of the experiment relative to B and B₀ (Band B_T and B₀). The upper graph represents quantification of the maturation efficiency as calculated by the percentage of band C_{4 h} to band B₀. D, shown is quantification of the stability of band C over the course of the experiment relative to B and C_{4 h} (band C_T/band C_{4 h}). Data for initial protein labeling and maturation efficiency (B and C, inset, respectively) represent the mean ± S.E. (n = 9 from 3 independent experiments labeled in triplicate). Time course graphs in C and D represent the mean ± S.E. with n = 6. Marked comparisons demonstrate significant differences as determined by Student's t test (*, p < 0.03; †, p < 0.007).