固有のアデニル酸キナーゼ活性が,ABCトランスポーターCFTRのゲート化を調節する
Christoph Randak1, Michael J Welsh
1Howard Hughes Medical Institute, Department of Internal Medicine and Physiology, Roy J and Lucille A Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
Cell
|December 31, 2003
まとめ
システィック・フィブロシス・トランスメブラン・コンダクトンス・レギュレータ (CFTR) タンパク質は,ATPアゼとアデニラートキナーゼの両方として作用し,二重の酵素活性を持っています. この二重機能,特にアデニル酸キナーゼ活性により,最小限のエネルギー消費でCFTRチャネルゲーティングを調節することができる.
科学分野:
- バイオケミストリー バイオケミストリー
- 分子生物学は分子生物学である.
- 細胞生理学 細胞生理学
背景:
- CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) はアニオンチャネルであり,ATP結合カセット (ABC) トランスポータースーパーファミリーの一員である.
- ゲートイオン流へのATPの水解に対するCFTRの要求は,アニオン輸送の被動的性質のため,謎に包まれています.
- ゲーティングのためにATP水解を利用する他のイオンチャネルは知られていません.
研究 の 目的:
- 単純なATP水解を超えてCFTRの酵素的活動を調査する.
- CFTRチャネルゲーティングが規制されるメカニズムを解明する.
- CFTR機能におけるヌクレオチド結合ドメインの役割を理解する.
主な方法:
- 精製したCFTRの酵素活性を検出し,特徴付けるための生化学分析.
- CFTRとATPとAMPの相互作用の分析.
- CFTRのATPアゼとアデニル酸キナーゼの活動に関する運動学的研究.
主要な成果:
- CFTRは,既知のATPアゼ活性に加えて,アデニラートキナーゼ活性 (ATP + AMP <=> ADP + ADP) を示しています.
- アデニラートキナーゼの活動は,ATPに対するポジティブな協力性を示し,核酸結合ドメインの潜在的二分化を示唆しています.
- ATPaseとアデニル酸キナーゼの活動は,第2の核酸結合領域内の共通のATP結合部位を共有しています.
結論:
- CFTRは二重の酵素機能であるATPアゼとアデニル酸キナーゼを持ち,チャネルゲーティングを調節する.
- 生理学的ヌクレオチド濃度では,アデニラートキナーゼ活性がCFTRゲーティングの主要な調節因子である可能性があります.
- この二重調節メカニズムは,ATPase活動にのみ依存するよりも,潜在的にエネルギー支出が低いゲート制御を可能にします.
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