Overview of GIRK2 structure. (A) Two opposing subunits of the GIRK2 structure (PDB accession no. 3SYA) are shown; subunits in the front and back are hidden for clarity. The approximated membrane boundaries between the TMD and CTD are indicated as gray bars. (B) PIP₂-binding site details: carbon atoms of the short-chain PIP₂ are colored cyan, dashed lines indicate interactions with different basic amino acids; the F192 side chain, forming the narrowest part of the HBC gate, is also shown. (C) Details of the selectivity filter region with classical K⁺ ion–binding sites (S0–S4) shown as sticks; “bowstring” interactions between E150 and R160 are indicated with dashed lines. (D) HBC and G-loop gate regions formed by F192 and G318/M319 residues are shown as sticks, respectively. (E) Simulation box after equilibration: protein embedded in POPC membrane (cyan lines); water is shown in red (represented as lines); K⁺ ions (purple) and PIP₂ (cyan lipid tail) are indicated as spheres.