Three unique lowest frequency modes of the CTD engaged Kir2.2 structure. Ribbon and sphere diagrams of Kir2 tetramer are color coded by the extent of the movement along each mode, with the maximum and minimum movement colored red or blue, respectively. Small arrows originating from every Cα atom show the direction as well as the magnitude of the respective residue movement along the mode. Side, top-down, and bottom-up views are shown for each mode. The gray arrows show the global motions of the TMD and the CTD along each mode.