野生型と変異型のシェイカー・カリウムチャネルにおけるゲーティング・チャージの大きさ
N E Schoppa1, K McCormack, M A Tanouye
1Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510.
まとめ
ボルテージゲートイオンチャネルは,開く時に電荷を移動させます. 直接測定では,シェイカーのカリウムチャネルで12.3電荷 (e0) の高い電荷移動 (q) が明らかにされ,以前の推定値とは異なる.
科学分野:
- 分子生物学は分子生物学である.
- バイオフィジックス 生物物理学
- 神経科学は神経科学である.
背景:
- ボルトゲートイオンチャネルは,細胞の電気信号伝送に不可欠です.
- 彼らの機能は,電荷の移動を含む膜ポテンシャルに敏感です.
- 以前の電荷の位移の推定値 (q) は間接的であり,4-8e0.0の範囲であった.
研究 の 目的:
- シェイカーのカリウムチャネルの開通時に電荷の移動 (q) を直接測定する.
- 変異が電圧感受性と電荷移動に与える影響を調査する.
- 電圧依存チャネル活性化のモデルを精錬する.
主な方法:
- ドロソフィラ・メラノガスター (Drosophila melanogaster) シェイカー29-4のカリウムチャネルにおける電荷の移動を測定するために,電気生理学的技術を使用した.
- 電圧感受性を変化させるために,部位指向型変異を生成した.
- チャンネルアクティベーションの電圧依存性を分析した.
主要な成果:
- ワイルド型のシェイカーチャネルにおける電荷の移動 (q) を直接測定すると,12.3 e0.0 が得られました.
- 変異したShakerチャネルは,電圧感受性が低下し,同様の高いq値を示した.
- これらの発見は,以前の推定値に異議を唱え,変異体におけるバランスの変化を示唆している.
結論:
- シェイカーチャネルゲーティングに関連した電荷の動きは,以前に推定されたものより大幅に大きい.
- 電圧感受性に影響する変異は,充電位移を比例して減少させない.
- 電圧依存のステップで変化した均衡を組み込んだモデルは,変異チャンネルでの結果を説明します.
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