ATP-ガンマ-Sによるスイカのアクソンにおける細胞内pH調節システムのpH感受性活性化

W F Boron¹, E Hogan, J M Russell

¹Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06510.

Nature

|March 17, 1988

まとめ

細胞内のpHの調節は,細胞の機能に不可欠です. この研究では,ATPが消費されるのではなく,pHバランスのために不可欠な,塩化塩酸ビカルボネート交換器を活性化することが示されています.

科学分野:

細胞生理学細胞生理学
メンブレーン輸送メンブレーン輸送
バイオケミストリーバイオケミストリー

背景:

細胞内pH (pHi) 調節は,細胞の機能と活性化に極めて重要です.
塩化塩酸と二酸化炭素の交換は,多くの細胞タイプにおける主要なpHi調節因子である.
イカのアクソンのこの交換器に対するATPの要求は,機械的に不明のままである.

研究の目的:

ナトリウムに依存した塩化物-二酸化炭素交換器の機能におけるATPの役割を解明する.
トランスポーター機能のATP水解 (ポンプ仮説) とATP活性化 (活性化仮説) を区別する.

主な方法:

非水解性ATPアナログであるATP-gamma-S.を用いたイカのアクソンの透析.
Na+依存のCl−HCO3交換器によるpH調節におけるATPの役割の調査.

主要な成果:

この研究は,ATPがステキオメトリック的に消費されないことを実証し,ポンプ仮説を排除した.
結果は,交換器のpH依存の活性化にはATPが必要であることを示しています.
アクティベーションは,リン酸化またはトランスポーターまたはアクティベーターに直接ATP結合によって起こる可能性があります.

結論:

ATPは,塩化塩酸ビカルボネート交換器の活性化に不可欠であり,水解による直接的なエネルギー供給には欠かせません.
この発見は,細胞のpHホメオスタシスと細胞活性化プロセスにおける重要なメカニズムを明らかにしている.

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