Comparison of ATP-bound Kir6.1 and Kir6.2 structures. (A i) Overall structure of Kir6.2 bound to ATP (red label) viewed from the side showing CTD in the up position and R176 (magenta carbons) close to the plasma membrane (PDB ID 7TYS). (A ii) Closeup view of the structure near the inner membrane. (B) Same as A but of the structure of Kir6.1 bound to ATP (PDB ID 7MIT). Note the Kir6.1-CTD is translated toward the cytoplasm by 5.8 Å and counterclockwise rotated by 12.4° (viewed from the top). The interfacial helix (IF helix) straightens into a full helix and the C-linker unwinds into a loop, and R186 in the C-linker is too removed from the inner membrane to interact with activating phospholipids in the predicted PIP₂ binding pocket.