2孔ドメインのK+チャネルTASK2のpHゲーティングの構造的基礎
Baobin Li1,2,3, Robert A Rietmeijer1,2,3,4, Stephen G Brohawn5,6,7
1Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA.
Nature
|October 1, 2020
まとめ
TASK2チャネルは細胞の興奮性とpHバランスを制御する. 新しい構造は2つの異なるpH感知ゲート,細胞内と細胞外を明らかにし,陽子がTASK2チャネル活動を調節する方法を説明します.
科学分野:
- 分子生物学
- バイオ物理学
- 生理学
背景:
- TASK2 (KCNK5) チャンネルは,細胞の電気的興奮に不可欠なpHゲートされたカリウムチャンネルです.
- 呼吸を調節し,腎臓の pH ホメオスタシスを維持する上で重要な役割を果たします.
- TASK2チャネルにおけるpH依存ゲートの正確なメカニズムは解明されていない.
研究 の 目的:
- TASK2チャネルのpH依存ゲートの構造的基礎を決定する.
- 細胞内および細胞外pHによって制御される異なるゲートメカニズムを解明する.
主な方法:
- Mus musculus TASK2の高解像度構造を取得するために,冷凍電子顕微鏡 (cryo-EM) が使用されました.
- 構造は,脂質ナノディスクのオープンとクローズドチャネルの両方に決定されました.
- 分子分析は,ゲートに含まれる重要な残留物と形状の変化を特定することに焦点を当てました.
主要な成果:
- 以前から知られているカリウムチャネルゲートとは異なる2つの新しいゲートメカニズムが特定されました.
- 細胞内ゲーティングは,内ヘリクスのライシン残基のプロトネーションを含み,細胞質シールを形成します.
- 細胞外ゲーティングは,アルギニン残基のプロトネーションと,選択性フィルタに影響を与える構造変化を含む.
結論:
- この研究では,TASK2チャネルに2つのゲートシステムがあり,膜の両側でのpH変化に対応しています.
- 特定の残留物 (ライシンとアルギニン) のプロトネーションは,異なる細胞内および細胞外ゲートメカニズムの基礎となっている.
- これらの発見は,TASK2チャネルがpHの変動を感知し,それに反応してイオンフローを調節するメカニズム的な説明を提供します.
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