Molecular Mechanisms of Large-Conductance Ca2+-Activated Potassium Channel Activation by Ginseng Gintonin
Figure 6
Involvement of the Ca2+ bowl and RCK domain in gintonin-mediated BKCa channel activation. (a) The oocytes expressing wild-type or various mutant BKCa channels at the Ca2+ bowl were treated by bath application of gintonin (10 μg/mL) for 60 s, and peak outward currents were recorded. Mutations of the Ca2+ bowl caused a rightward shift of the gintonin concentration-response curve. (b) The oocytes expressing wild-type or RCK domain mutant BKCa channels, D433A or M579I, were treated with gintonin by bathing application for 60 s. Mutation of the RCK domain also caused a rightward shift of the gintonin concentration-response curve. (c) The oocytes coexpressing M1 muscarinic receptor or various mutant BKCa channels with M1 muscarinic receptor were treated by bath application of acetylcholine (100 μM), and peak outward currents were recorded. Mutations of the calcium bowl caused a rightward shift of the acetylcholine concentration-response curve. (d) Oocytes coexpressing wild-type with M1 muscarinic receptor or mutant BKCa channels at the RCK domain such as D433A or M579I with M1 muscarinic receptor were treated with gintonin by bathing application for 60 s. Mutations in the RCK domain caused a rightward shift of the gintonin concentration-response curve (mean ± S.E.M; -14 oocytes each).
