Figure 4.

The two forms of the GABA_B receptor activate Kir3.1+3.2A channels through different G_i/oα subunits. (A) Stimulation of both the GABA_B1a+2 and the GABA_B1b+2 receptor (100 μM baclofen) led to robust activation of the Kir3.1+3.2A channels. Currents were elicited as described in Fig. 1B. (B) Summary of data obtained from expression of the GABA_B1a, -1b, and -2 subunits alone, and when expressed as the dimeric receptors GABA_B1a+2 and GABA_B1b+2. (B and D) Bar charts summarizing the data obtained with the GABA_B1a+2 receptor (C) and the GABA_B1b+2 receptor (D) when the mutant G_i/oα mutants were co-expressed in PTx-treated cells. Open bars represent basal currents, and solid bars represent current in response to receptor stimulation. Numbers in parentheses refer to the number of cells recorded from for each experiment. Current density was measured at −100 mV.