細胞内ゲートの開口は,高親和の金属ブリッジによって定義されたシェイカーK+チャネルで開きます
Sarah M Webster1, Donato Del Camino, John P Dekker
1Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, Massachusetts 02115, USA.
Nature
|April 23, 2004
まとめ
電圧制御のカリウムチャネルは,神経細胞の信号伝達を制御する. 新しい発見は,バクテリアモデルとは異なるシェイカーチャネル構造を明らかにし,その低いイオン伝導性を説明する可能性がある.
科学分野:
- 分子生物学は分子生物学である.
- 神経科学は神経科学である.
- バイオフィジックス 生物物理学
背景:
- 電圧誘導のカリウムチャネルは,イオンフローを制御することによって,神経細胞の電気信号伝達を調節する.
- シェイカーチャネルのゲーティングメカニズムは,ニューロンの機能に極めて重要です.
- 現存するモデルでは,ゲーティングのためのバクテリアのチャネルにおけるヒンジーの動きを提案している.
研究 の 目的:
- シェイカー・カリウムチャネルの開いた状態における構造的制約を調査する.
- シェイカーチャネルのゲートメカニズムと細菌のカリウムチャネル (KcsAとMthK) を比較する.
- シェイカーとバクテリアのチャネル間のイオン伝導率の差異の構造的根拠を解明する.
主な方法:
- システインを含むサブユニット間の金属ブリッジを使用して,シェイカーのチャネル構造を調査しました.
- バクテリアのチャネルの既存の結晶構造と組み合わせて構造データを分析した.
- シェイカーとバクテリアのチャネル間の構造モチーフとゲートメカニズムを比較した.
主要な成果:
- シェイカー・チャネルの開いた状態で2種類のインターサブユニット金属ブリッジを特定しました.
- これらの橋は,内孔ヘリクスの構造と動きを制限する.
- シェイカーチャネルは,Pro-X-Proの曲線で,オープン状態でKcsAのようなバンドルクロスモチーフを維持している可能性が高い.
結論:
- シェイカーチャネルのゲーティングメカニズムは,MthKに提案されたヒンジモーションモデルとは異なる.
- シェイカーチャネルに保存されたプロリンモチーフは,内孔ヘリックス形状に影響を与えます.
- シェイカーチャネルにおけるより狭い束の交差は,細菌の親類と比較して,その低いイオン伝導性を説明する可能性があります.
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Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.
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Ligand-gated ion channels fall into three subfamilies. The 'Cys-loop' includes the nicotinic acetylcholine receptors, γ-aminobutyric acid (GABA), glycine, and 5-hydroxytryptamine receptors. The second one is the 'Pore-loop' channels that include the...
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