Figure 3. Activation of G proteins with GTP-γ-S inhibits DAT function in heterologous systems.

(A) [³H]-DA uptake assays in Xenopus laevis oocytes expressing DAT after intracellular injection with water (white bar, n = 8), 10 µM GTP-γ-S (black bar, n = 8), or 10 µM GDP-β-S (gray bar, n = 8). (B) Specific [³H]-DA uptake and kinetic analysis for HEK293-DAT permeabilized with streptolysin-O (SLO) and dialyzed with 50 µM GTP-γ-S (white circles, n = 3). or control buffer (black circles, n = 3). **p<0.01.