FIGURE 6.

The PKA-dependent activity of CFTR mutants R764A and R766A. A, unit channel currents across inside-out membrane patches excised from transfected HEK-293T cells expressing R766A by using a holding potential (+60 mV). In the presence of 1.5 mm ATP, PKA was added gradually until the current was no longer increased. The arrows indicate the final concentrations. N-Ethylmaleimide (NEM) was used to increase the channel activity (9). 200 μm glibenclamide or 10 μm CFTRinh₁₇₂ was used to inhibit the channel activity. B, PKA titration curves for CFTR mutants R764A and R766A (n = 3–5). WT CFTR was a control.