Figure 3.

Comparison of d- and l-[³H]aspartate and l-[³H]glutamate transport in proteoliposomes containing S440G transporters. Conditions are the same as those given in the legend to Fig. 2, with 0.15 M of NaCl (■), LiCl (●), and choline chloride (▴) as external media containing the radiolabeled substrates. The 10-min values in sodium-containing media are taken as 100% values. Those were 466, 267, and 26 pmol/mg protein for d- and l-aspartate and l-glutamate, respectively, measured with 0.25, 0.17, and 0.043 μM as external concentrations, respectively. In the case of wild type (not depicted in the figure) the 10-min values were 1,160 (NaCl), 18 (LiCl), and <1 (choline chloride) pmol/mg protein for d-aspartate; 669 (NaCl), 13 (LiCl), and <1 (choline chloride) pmol/mg protein for l-aspartate; and 101 (NaCl), 1.4 (LiCl), and <1 (choline chloride) pmol/mg protein for l-glutamate.