Key residue Unlocks Dual PIP2-Dependent and Independent Gating in G Protein-Gated Inwardly Rectifying Potassium Channels

Abstract G protein-gated inwardly rectifying potassium (GIRK) channels mediate membrane hyperpolarization in response to G protein-coupled receptor activation and are critical for regulating neuronal excitability. The membrane phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2) is essential for regulating a large family of ion channels, and disruptions in PIP2 interactions contribute to some neurological diseases. Structural analyses have identified key residues in PIP2-mediated gating of the GIRK2 channel. Notably, Arginine-92 (R92), a highly conserved basic residue at the membrane interface in GIRK2, interacts with PIP2 as well as cholesteryl hemisuccinate (CHS), a potentiator of GIRK2. Here, we used a combination of electrophysiological assays, fluorescent K+ flux measurements, cryo-electron microscopy, and molecular dynamics simulations, and find that mutations at R92 (Y, F, and Q) not only alter PIP2 sensitivity but can also reveal a novel gating mechanism that is independent of PIP2. These findings indicate that R92 plays a crucial role in modulating GIRK2 channel gating, offering new insights into developing potential therapeutic targets for treating neurological disorders linked to GIRK channel dysfunction. Competing Interest Statement The authors have declared no competing interest.