FIGURE 3.

Probing solvent accessibility of TM2 residues. COS-1 cells transiently transfected withTM2 cysteine mutants were preincubated in buffer for 10 min at room temperature with or without 1 mm MTSET, then assayed for [³H]TCA uptake. Uptake results were first expressed as a ratio of uptake with MTSET pretreatment over uptake without MTSET pretreatment, then the final results were expressed as the percentage of C270A. Bars represent the S.E. of three experiments with triplicates each time.