Ras in Rafの活性化に対する要求は,Rafをプラズマ膜にターゲットにすることで克服されます
S J Leevers1, H F Paterson, C J Marshall
1Section of Cell and Molecular Biology, Institute of Cancer Research, Chester Beatty Laboratories, London, UK.
Nature
|June 2, 1994
まとめ
Rasは,細胞シグナル伝達における重要なタンパク質キナーゼであるRafの膜アンカーとして機能する. この局所化はRafの活性化に不可欠であり,他の信号もプロセスに寄与します.
科学分野:
- 細胞の信号伝達経路は,
- 分子生物学は分子生物学である.
- バイオケミストリー バイオケミストリー
背景:
- 保存されたシグナル伝達経路には,Ras,Raf,MAP-キナーゼキナーゼ,MAPキナーゼが含まれています.
- Ras-GTPはRafと相互作用しますが,Ras-GTPによる直接キナーゼ活性化はインビトロでは観察されていません.
- アクティベーションされたRafはRasを必要としないので,Rasには明確な役割があることを示唆しています.
研究 の 目的:
- ラフの活性化におけるラスの役割を調査する.
- アクティベーションのためにRasがRafをプラズマ膜にローカライズするために必要かどうかを判断する.
- RasがRafの活動に影響を与えるメカニズムを解明する.
主な方法:
- 同免疫プレシピテーションの測定は,RasとRafの相互作用を検出する.
- In vitroキナーゼアッセイで,Rafの活性性を評価する.
- 融合タンパク質構造:K-Ras4B) 膜局所化信号をRaf.にリンクする.
- エンジニアリングによるRaf構造を発現する細胞におけるRaf活性化の分析.
主要な成果:
- Ras-GTPは,Rafキナーゼの活性を直接刺激するものではありません.
- Rasは,活性化,溶解したRafの製剤では検出されません.
- Rafは,活性Rasを発現する細胞のプラズマ膜と結合する.
- K-Ras(4B) 膜局所化信号を持つ Raf 構造は構成的に活性であり,Ras.から独立して EGF によってさらに活性化されます.
結論:
- Rasは,Rafの制御された膜結合アンカーとして機能する.
- Rasによって媒介されるプラズマ膜の局所化は,Rafの活性化に不可欠です.
- Ras以外の追加のシグナルイベントは,Rafの活性化に寄与する.
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