Faculty, Staff and Student Publications

Language

English

Publication Date

11-24-2025

Journal

Nature Communications

DOI

10.1038/s41467-025-66730-8

PMID

41285859

PMCID

PMC12748987

PubMedCentral® Posted Date

11-24-2025

PubMedCentral® Full Text Version

Post-print

Abstract

Gi/o protein-coupled receptors (GPCRs) inhibit cardiac and neuronal excitability via G protein-activated K+ channels (GIRK), assembled by combinations of GIRK1 - GIRK4 subunits. GIRKs are activated by direct binding of the Gβγ dimer of inhibitory Gi/o proteins. However, key aspects of this textbook signaling pathway remain debated. Recent studies suggested no Gi/o-GIRK pre-coupling and low (>250 µM) Gβγ-GIRK interaction affinity, contradicting earlier sub-µM estimates and implying low signaling efficiency. We show that Gγ prenylation, which mediates Gβγ membrane attachment required for GIRK activation, also contributes to the Gβγ-GIRK interaction, explaining the poor affinity obtained with non-prenylated Gβγ. Using quantitative protein titration and electrophysiology in live Xenopus oocytes, Gβγ affinity for homotetrameric GIRK2 ranges from 4-30 µM. Heterotetrameric GIRK1/2 shows a higher Gβγ apparent affinity due to the Gβγ-docking site (anchor) in GIRK1, which enriches Gβγ at the channel. Biochemical approaches and molecular dynamic simulations reveal that the Gβγ anchor is formed by interacting N-terminal and distal C-terminal domains of the GIRK1 subunits, distinct from the Gβγ-binding “activation” site(s) underlying channel opening. Thus, the affinity of Gβγ-GIRK interaction is within the expected physiological range, while dynamic pre-coupling of Gβγ to GIRK1-containing channels through high-affinity interactions further enhances the GPCR-Gi/o-GIRK signaling efficiency.

Keywords

G Protein-Coupled Inwardly-Rectifying Potassium Channels, Animals, GTP-Binding Protein beta Subunits, GTP-Binding Protein gamma Subunits, Oocytes, Humans, Xenopus laevis, Signal Transduction, Protein Binding, HEK293 Cells, Potassium channels, Ion channel signalling

Published Open-Access

yes

Download

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.