(A) Surface charge representation of KCNQ1EM. Two positive charged pockets, which are next to the hinge region (loop connecting S4 to the S4-S5 linker) and HB helix, are indicated by yellow arrows.
(B) Zoomed-in view of the hinge region and map of the key residues that are important for PIP2 regulation of the KCNQ1EM channel. The hinge region is colored in red, and c-alphas of key residues are shown as yellow spheres with side chains in stick representation.
(C) Sequence alignment of the hinge region connecting S4 and the S4-S5 linker.
(D) Cartoon depicting the idea that PIP2 couples the voltage senor domain and the pore domain, in contrast with Kv1.2-2.1. The grey box and orange cylinder represents the voltage sensor domain containing positive charged “+” amino acids on the S4 helix. The pore domain is colored yellow and the S4-S5 linker green. PIP2 is shown as a purple hexagon. The red loop represents the hinge region connecting S4 to the S4-S5 linker. The black arrow signifies the process of membrane depolarization.