FIGURE 3.

Impact of MTS application on [³H]5-HT transport activity of hSERT TM6 Cys mutants. Aqueous accessibility of TM6 Cys mutants was assessed by application of 0.25 mm MTSEA (A), 1 mm MTSET (B), or 10 mm MTSES (C). Transiently transfected HEK-293T cells were incubated with an MTS reagent from 10 min at room temperature and then subjected to a [³H]5-HT uptake assay as described under “Experimental Procedures.” Results are expressed as the percent of untreated transporter activity for each mutant and represent the means ± S.E. from at least three uptake experiments. TM6 Cys mutants were compared with C109A using one-way ANOVA with a post hoc Dunnett's test, with * indicating p < 0.05. n.t., not tested.