Cell surface expression of the various Kv channels in HEK293 cells. The Kv channel surface expression was detected using the cell surface biotinylation of HEK293 cells transfected with the wild-type/mutant Kv channels. The left panels were the biotinylated membrane protein samples, and the right panels were total protein samples. (A) Sample images showing endogenous or transfected wild-type/mutant Kv2.1 channel expression. (B) Sample images showing endogenous or transfected wild-type/mutant Kv2.2 channel expression. (C) Sample images showing endogenous or transfected wild-type/mutant Kv1.2 channel expression. The signals of the intracellular protein beta-tubulin were detected only in the total protein samples (right panels) and not in the biotinylated surface protein samples (left panels). Endogenous cell surface protein expression of the Kv2.1, Kv2.2, and Kv1.2 channels was undetectable. (D) The mutations did not alter the cell surface expression of the Kv channels in HEK293 cells (n = 3, p > 0.05, WT versus mutants).