FIGURE 5.

Tandem channel subunits clarify the effect of the MT subunit. A, schematic of expected channel combinations when cells express the hKv7.4 WT and G321S MT subunit or tandem clones. B, the tandem clone has two epitopes, HA and myc, located at the extracellular loop between the S1 and S2 transmembrane domains of Kv7.4a WT and G321S MT, respectively. Anti-HA and anti-myc antibodies were used for the immunofluorescence assay with the conditions either permeabilized or non-permeabilized. Scale bars = 10 μm. C, representative traces showing the whole-cell recording from CHO cells transfected with tandem clones alone or with CaMDN. The current traces were recorded from a holding potential of −70 mV to step potentials ranging from −90 to 60 mV using voltage increments of 10 mV. Tail currents were recorded at −30 mV. D, plots of current (I) density (picoampere/picofarad)-voltage relations of currents were derived from CHO cells expressing tandem clones with either empty vector or CaMDN. E, CHO cells were expressed with either hKv7.4a or tandem clones for 24 h. After preparation of cell lysates, immunoprecipitation was accomplished with Kv7.4 antibody to test CaM binding to the channel subunit.