FIGURE 5.

A dominant negative mutant of SEC24D, but not of SEC24C, decreases substrate uptake by SERT-K610Y (A) by causing intracellular retention of the mutant transporter (B). HEK293 cells were transiently transfected with a plasmid driving the expression of SERT-K610Y, in the absence or presence of the increasing amounts of plasmids (plasmid ratio indicated in the figure caption) encoding dominant negative mutants of SEC24C (SEC24C-⁷⁹⁶DD⁷⁹⁷-VN) and SEC24D (SEC24D-⁷³³DD⁷³⁴-VN). Cell surface levels of SERT-K610Y were quantified by measuring specific [³H]5-HT uptake (A) or visualized by confocal microscopy (B). The bars represent the means ± S.E. from four independent experiments (means ± S.E.). *, significantly different (p < 0.01) from control and dominant negative SEC24C (one-way ANOVA, followed by Tukey's post hoc test). There was no statistically significant difference in uptake by cells transfected with control plasmid and a dominant negative version of SEC24C.