FIGURE 6.
Site-directed mutagenesis identified the region in exon2 that is responsible for the molecular/biophysical characteristics of BKαΔe2. A, diagram of the mutants selected for this study. B–D, current-voltage relationships of Pax-sensitive whole cell components obtained from cells that expressed mutants of Δ1-Δ6 (B), MTS, VKD, WAG, VMI, SAQ, TLT, GR, and VL (C) and S171, Q173, G177 and R178 (D) are shown (left). Current densities of Pax-sensitive component at +120 mV in cells expressing mutants are summarized (middle). The ratio of anti-FLAG-positive cells analyzed by NP labeling is illustrated as in Fig. 4B (right). See also supplemental Table S4. *, p < 0.05; **, p < 0.01 versus WT by Dunnett's test. E, voltage dependence was examined in mutants that showed substantial reduction of current density without marked reduction of membrane trafficking, i.e. Δ3, MTS, VKD, WAG, VMI, TLT, VL, S171 and Q173. Intracellular Ca2+ level was fixed at pCa 6.5. Relationships between G/Gmax and voltage were fitted with Boltzmann equation. F, the values of half activation voltage (V1/2) of mutants were compared. *, p < 0.05; **, p < 0.01 versus WT.