Fig. 6.
The effect of ONOO− on cysteine mutants of hDAT. Intact EM4 cells stably expressing wild-type hDAT or the indicated cysteine mutants were exposed to ONOO− (1 mm) for 10 min at 25°C. Cells were washed three times with KRH, and the uptake of3H-DA was determined. X7C is a mutant of the wild-type (WT) hDAT in which all intracellular and extracellular loop cysteines were mutated (see Materials and Methods). CD-DAT is a cysteine-deficient mutant that contains reduced cysteines only in its first (C135) and third (C342) intracellular loops. X7C-M342C is a mutant into which only cysteine 342 has been reintroduced into X7C. Data are expressed as a percentage of control, where each mutant (untreated) served as its own control for ONOO− treatment. The results represent mean ± SEM of five to seven experiments run in triplicate. *Indicates that the effect of ONOO− was significantly different from its effect on WT hDAT (p < 0.05; Bonferroni's test).