Fig. 3. Released CFTR fragments are heterogeneous. (A) Supernatants of CFTR-degradation reactions were collected at the times indicated and analyzed by SDS-PAGE (7-12% gel) and autoradiography. Inhibitor concentrations were 100 µM for MG132, ALLN, clasto-lactacystin ß-lactone (ß lactone) and 40 µM for hemin. Hexokinase and 2-deoxyglucose were added to deplete ATP (–ATP). (B) Total products of the degradation reaction are shown to demonstrate the rate of disappearance of CFTR protein. High M_r material in lanes 26-30 (hemin treatment) represents ubiquitylated CFTR products (Xiong et al., 1999). Exposure of the top panels was longer (5x) than the bottom panels.