Figure 3.

SCAM experiments with whole-cell recordings. (A) A continuous recording of whole-cell I106C/Cysless channel current in response to an external application of MTSES. The I-V relationships for net CFTR currents before (b-a) and after (c-a) MTSES modification were shown below the trace. (B) The same protocol was adopted for S108C/Cysless mutant channels, which exhibit little response to external MTSES. However, reversible inhibition by CFTRinh-172 shows that the current observed was indeed due to the activation of CFTR. (C) Summary of whole-cell SCAM results on the eight residues, G103C-D110C. Data at ±80 mV were presented to illustrate the unique voltage-dependent inhibition by MTSES at position 107. The number of cells was labeled at the end of each bar. ^∗ indicates no detectable current for G103C-CFTR.