Molecular Mechanisms of Large-Conductance Ca2+-Activated Potassium Channel Activation by Ginseng Gintonin
Figure 7
Double mutations of CaM kinase II and Ca2+ bowl or RCK domain further attenuate gintonin-mediated BKCa channel activation. (a) Time-current relationship after application of gintonin (10 μg/mL) or ginsenoside Rg3 (100 μM) for 60 s in oocytes coexpressing BKCa channels and CaM kinase II + Ca2+ bowl mutants. Insets, the representative peak outward current amplitude at +40 mV from a holding potential of −80 mV was measured in the presence of gintonin or ginsenoside Rg3. (b) Time-current relationship after application of gintonin (10 μg/mL) or ginsenoside Rg3 (100 μM) for 60 s in oocytes coexpressing BKCa channels and CaM kinase II + RCK domain mutants. Inset, the representative peak outward current amplitude at +40 mV from a holding potential of −80 mV was measured in the presence of gintonin or ginsenoside Rg3. (c) Coexpression of BKCa channels with CaM kinase II + Ca2+ bowl mutants caused a further rightward shift of the gintonin concentration-response curve. (d) Coexpression of BKCa channels with CaM kinase II + RCK domain mutants caused a further rightward shift of the gintonin concentration-response curve (mean ± S.E.M; oocytes each).
