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Updated: Jun 21, 2026

A Kinetic Fluorescence-based Ca2+ Mobilization Assay to Identify G Protein-coupled Receptor Agonists, Antagonists, and Allosteric Modulators
Published on: February 20, 2018
Specificity of Gbetagamma signaling depends on Galpha subunit coupling with G-protein-sensitive K(+) channels
Xian Geng1, Xiao-na Du, Radda Rusinova
1Department of Pharmacology, Hebei Medical University, Shijiazhuang, People's Republic of China.
Abstract:
Many neurotransmitters activate G-protein-gated inwardly rectifying K(+) (Kir3) channels by stimulating G-protein-coupled receptors. However, in native systems, only receptors coupled to pertussis-toxin (PTX)-sensitive G proteins (Gi/Go) have been shown to be able to activate Kir3 channels through the betagamma subunits of G proteins (Gbetagamma), whereas activation of receptors coupled to PTX-insensitive G proteins such as Gq or Gs do not activate Kir3 channels. The question remains as to how signaling specificity is achieved and what are its key determinants. In this study, we have used the Xenopus oocyte expression system to investigate specific activation of Kir3 channels by heterotrimeric G proteins. We have demonstrated the activation of Kir3.4 channels by agonist stimulation of non-PTX-sensitive G proteins under conditions of Galpha subunit overexpression. We present evidence to suggest a key role for the coupling efficiency of Galpha subunits in determining the specificity of Gbetagamma signaling to the channel.
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