Fig. 4.

Affinity of the fluorescent substrate ASP⁺ is unaffected by the T62A- or T62D-hDAT mutations. As detailed in Materials and Methods, (A) uptake of 10 nM [³H]DA for 3 minutes or (B) binding of [³H]WIN 35,428 for 30 minutes in WT- (▪), T62A- (▴), and T62D-(◊) hDAT HEK cells was measured as a function of varying ASP⁺ concentrations. Data are expressed as the percent of the control without ASP⁺ and are shown as the mean ± S.E.M; n = 2 experiments performed in triplicate. The IC₅₀ (μM) values with 95% confidence intervals are reported in Results.