FIGURE 6.
Modification of introduced cysteines by pretreatment with external MTSET. A and B, shown are example leak-subtracted I-V relationships for each of the five mutants named, showing the effects of application of internal MTSES (200 μm) after maximal channel activation with PKA (20 nm), ATP (1 mm), and PPi (2 mm). Patches were excised from cells that had been pretreated in two different ways (see “Experimental Procedures”), no pretreatment (A), pretreated with external MTSET (5 mm, for 5 min, B). C, shown is a comparison of the effects of MTSES on macroscopic current amplitude at −80 mV after the two different pretreatments shown in A and B. The asterisk indicates a significant difference from no pretreatment conditions (p < 0.005). D, shown is the mean rectification ratio for control CFTR currents (recorded before exposure to internal MTSES) under these two sets of conditions, indicating that pretreatment with external MTSET significantly decreases the rectification ratio in both T338C and S341C (asterisks, p < 0.05). Data are the means from 3–8 patches.