Figure 2. VGLUT2 does not transport Cl⁻ during glutamate transport.

A. Uptake of radiolabeled Cl⁻. In the presence of 5 mM glutamate, ³⁶Cl⁻ uptake by liposomes or VGLUT2-containing proteoliposomes was measured in the presence (+) or absence (−) of Val. In some experiments, nystatin was included to estimate [³⁶Cl⁻] at equilibrium. ³⁶Cl⁻ uptake by VGAT at 1 min is shown as a positive control for active Cl⁻ transport. Essentially the same results were obtained when 10 % (w/w) cholesterol was included in the proteoliposomes. Error bars represent mean ± SEM; n = 3. B. Comparison of glutamate or GABA-evoked Cl⁻ uptake by VGLUT or VGAT, respectively, as revealed by SPQ fluorescence. SPQ-trapped VGLUT2-containing proteoliposomes were prepared and SPQ fluorescence intensity was monitored. Proteoliposomes containing either VGAT or the E213A mutant VGAT were also measured. Additions: KCl, 10 mM; GABA, 5 mM; glutamate, 5 mM; glycine, 5 mM; Val, 2 μM; nystatin, 250 μM. A principle of assay system was also illustrated. See also Figure S2.