Activation of Gβγ with mSIRK resulted in an inhibition of DAT activity in heterologous systems.

<p>(<b>A</b>) Oocytes expressing DAT (white bars) or EAAT1 (gray bars) were incubated for 30 min with 0.5% DMSO (DAT/n = 3; EAAT1/n = 25), 5 µM mSIRK (DAT/n = 20, EAAT1/n = 23), or 25 µM mSIRK (DAT/n = 15, EAAT1/n = 15) before uptake assays with [H³]-DA or [³H]-Glutamate, respectively. (<b>B</b>) Dose-dependent inhibition of [³H]-DA uptake in HEK293-DAT cells by mSIRK (n = 4, white circle). (<b>C</b>) 5 min pre-incubation of HEK293-DAT cells with 10 µM mSIRK produced a reduction of V_max with no changes in K_m (n = 3). (<b>D</b>) In HEK293-DAT, 10 µM mSIRK reduced uptake (control, black bar, n = 32; mSIRK, white bar, n = 15). The inhibitory effect of 10 µM mSIRK was attenuated in HEK-DAT cells expressing GRK2ct (control, n = 16; mSIRK, n = 16). **p<0.01 or *p<0.05.