Figure 2.

Effect of DTE on hASCT2 transport activity. The reconstitution was performed as described in Section 4.5. (A) Transport was started by adding 50 μM [³H]Gln and 50 mM external Na-gluconate at time zero to proteoliposomes containing 10 mM Gln in the presence (●) or absence (○) of 10 mM DTE. The transport reaction was stopped at the indicated times, as described in Section 4.6. (B) Transport was started by adding 50 μM [³H]Gln and 50 mM external Na-gluconate at time zero to proteoliposomes reconstituted with hASCT2 and containing 10 mM Gln upon 30 s of incubation with the indicated concentrations of extraliposomal DTE. In the inset, the dependence on incubation time is reported using 10 mM DTE. Transport activity was shown as fold of activation, in the presence of DTE, with respect to absence of DTE. The transport reaction was stopped after 30 min as described in Section 4.6. (C) Kinetic analysis of hASCT2 transport activity. Transport rate was measured adding [³H]Gln at the indicated concentrations and 50 mM Na-gluconate, in the presence (●) or absence (○) of 10 mM DTE, to proteoliposomes containing 10 mM Gln. The transport reaction was stopped after 15 min as described in Section 4.6. Data were plotted according to Lineweaver-Burk as reciprocal transport rate vs reciprocal Gln concentration. (A–C) Results are means ± S.D. from three experiments.