Structure of Kcv and its orientation in the lipid bilayer. (A) Comparison of the KcsA and Kcv protein sequences between two transmembrane domains, including the pore helix and the selectivity filter (top). The arrangement of different domains in Kcv was predicted based on the KcsA structure (bottom). Leu70 is marked in red. (B) Orientation of the Kcv channel in the lipid bilayer, as demonstrated by a series of experiments.