CTD twisting motions observed in open Kir6.2 cryo-EM structures. (a and b) Kir6.2 cryo-EM structure in the closed state (gray; PDB accession no. 7U24) is overlaid with open-state Kir6.2 cryo-EM structures in which the opening was mediated either by gain-of-function mutations (pale orange; PDB accession no. 7S5T) (a) or by PIP₂ binding (orange: PDB accession no. 8TI2) (b). Diagonal distances of G324 and E229 are shown in the Å unit. Curved arrows indicate a motion that reflects the conformational changes in the CTD from the closed to open transition.