1990 Fiscal Year Final Research Report Summary
The Mechanism of Ca^<2+>-regulated Anion Channel
| Project/Area Number |
63480511
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
分子遺伝学・分子生理学
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| Research Institution | Osaka University |
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Principal Investigator |
OHKAWA Taka-aki Osaka University, General, 教養部, 助手 (30029714)
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| Project Period (FY) |
1988 – 1990
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| Keywords | Chara / Ca^<2+> dependence / calmodulin-antagonist / Cl^- channel / inside-out patch / Voltage dependence / Open probability / plasmolysis |
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| Research Abstract |
The inside-out patch-clamp technique was applied to the plasmolyzed plasmalemma of internodes of Chara corallina without enzymatic treatment. We found two different types of channel activity that were C1^- -sensitive. Both types of channel were Ca^<2+> -dependent. However, the one that exhibited greater dependence on Ca^<2+> ions was the focus of our studies, and we named it the Ca^<2+> -dependent Cl^- -sensitive anion channel. When the concentration of Ca^<2+> ions on the cytoplasmic side was 1.0 uM, the Ca^<2+>-dependent Cl^- -sensitive channel opened most frequently between approximately -80 and -100mV. At 10 uM Ca^<2+>, it opened less frequently, and at 0.1 uM Ca^<2+> it scarcely opened at all. These observations indicate that the anion channel of interest is voltage-dependent over a restricted range of concentrations of Ca^<2+> ions. The dependence on Ca^<2+> and voltage of the channel can explain the behavior of the excitable Ca^<2+>-activated Cl^- channel in the Chara plasmalemma. The channel activity was blocked by several antagonists of calmodulin.
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