Evidence for oligomerization between GABA_B receptors and GIRK channels containing the GIRK1 and GIRK3 subunits

Abstract

The stimulation of inhibitory neurotransmitter receptors, such as γ-aminobutyric acid type B (GABA(B) ) receptors, activates G protein-gated inwardly-rectifying K(+) (GIRK) channels, which influence membrane excitability. There is now evidence suggesting that G protein-coupled receptors and G protein-gated inwardly-rectifying K(+) [GIRK/family 3 of inwardly-rectifying K(+) (Kir3)] channels do not diffuse freely within the plasma membrane, but instead there are direct protein-protein interactions between them. Here, we used bioluminescence resonance energy transfer, co-immunoprecipitation, confocal and electron microscopy techniques to investigate the oligomerization of GABA(B) receptors with GIRK channels containing the GIRK3 subunit, whose contribution to functional channels is still unresolved. Co-expression of GABA(B) receptors and GIRK channels in human embryonic kidney-293 cells in combination with co-immunoprecipitation experiments established that the metabotropic receptor forms stable complexes with GIRK channels. Using bioluminescence resonance energy transfer, we have shown that, in living cells under physiological conditions, GABA(B) receptors interact directly with GIRK1/GIRK3 heterotetramers. In addition, we have provided evidence that the receptor-effector complexes are also found in vivo and identified that the cerebellar granule cells are one neuron population where the interaction probably takes place. Altogether, our data show that signalling complexes containing GABA(B) receptors and GIRK channels are formed shortly after biosynthesis, probably in the endoplasmic reticulum and/or endoplasmic reticulum/Golgi apparatus complex, suggesting that this might be a general feature of receptor-effector ion channel signal transduction and supporting a channel-forming role for the GIRK3 subunit.

Regulator of G Protein Signaling 6 (RGS6) Protein Ensures Coordination of Motor Movement by Modulating GABAB Receptor Signaling

“…In addition, RGS6 exhibited co-localization with GIRK1, GIRK2, and GABA B R2 in these cells (Fig. 7B), a finding consistent with previous reports of coupling between GABA B Rs and functional GIRK channels in neurons (37) and indicative that RGS6 is positioned within these cells to influence G␤␥-induced GIRK channel activity.…”

Molecular Pharmacology ofδ-Opioid Receptors

“…The idea that GPCRs and Kir3 channel association may take place beyond overexpression systems is supported by biochemical and functional observations obtained with native dopamine D 2 and GABA B receptors in brain membranes. Indeed, Kir3 subunits were coimmunoprecipitated from brain membranes with either of these receptors (Lavine et al, 2002;Ciruela et al, 2010). In addition, cocaine or amphetamine administration leads to cointernalization of GABA B and Kir3 subunits in the VTA and prelimbic cortex (Padgett et al, 2012;Hearing et al, 2013), further arguing in favor of an association between receptors and effectors, which supports their joint regulation.…”

Novel Mechanism of Voltage-Gated N-type (Cav2.2) Calcium Channel Inhibition Revealed through α-Conotoxin Vc1.1 Activation of the GABAB Receptor

“…One explanation may be direct contact between GABA B R and Ca v 2.2, and such an interaction could involve G proteins. GABA B R physically interacts with the GIRK channel to modulate its function via G proteins (Fowler et al, 2007;Ciruela et al, 2010). However, Vc1.1 does not appear to activate GIRK channels (T. Huynh and P. Slesinger, unpublished observation; see also McIntosh et al, 2009).…”