トランスロコンサブコンプレックスへの分泌前駆体ポリペプチドの結合はBiPによって調節される
1Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley 94720, USA.
Cell
|January 10, 1997
まとめ
Sec62p,Sec71p,Sec72pは,ER膜に分泌タンパク質を結合する複合体を形成しています. BiPとSec63pによるATP依存の放出は,早期ER転位に不可欠である.
科学分野:
- 細胞生物学 細胞生物学
- 分子生物学は分子生物学である.
- タンパク質の密輸 タンパク質の密輸
背景:
- 細胞機能には,エンドプラズマ網膜 (ER) 膜を通じた分泌タンパク質の転位が不可欠である.
- このプロセスは,前駆体タンパク質のドッキング,挿入,およびタンパク質伝導チャネル (トランスロコン) 経由の転位を含む.
- 前駆物質の初期関与と放出を制御する正確なメカニズムは,まだ完全に理解されていません.
研究 の 目的:
- ER膜における分泌前駆体の初期結合に関与するタンパク質複合体を特定し,特徴づけること.
- ER転位の初期段階におけるSec62p,Sec71p,Sec72p,BiP,Sec63pを含む特定のタンパク質の役割を解明する.
- 前駆物質の結合と放出を規制する規制メカニズムを定義する.
主な方法:
- タンパク質とタンパク質の相互作用を研究するための生化学分析.
- トランスロケーションステップのインビトロ再構成.
- 異なるATP条件下でのタンパク質結合と放出運動の分析.
- 重要なタンパク質の機能を評価するための遺伝子操作.
主要な成果:
- Sec62p,Sec71p,Sec72pは,ER膜に分泌前駆体を結合する異なったトランスロコンサブコンプレックスを形成する.
- 先駆体結合は,無傷の信号配列に依存し,ATPがない場合に発生します.
- このサブコンプレックスからATP媒介による前駆体放出は,ルメナルチャペロンBiPとSec63pとの相互作用によって促進される.
- このBiP-Sec63p媒介による放出は特異的で,転位プロセスの初期に発生する.
結論:
- Sec62p-Sec71p-Sec72p複合体は,ER膜の分泌前駆体のための最初のドッキングサイトとして機能します.
- BiPとSec63pは,膜結合複合体からの前駆物質の早期放出を調節し,その後の転位を促進する上で重要な役割を果たします.
- これらの発見は,タンパク質の転位が ER ルーメンに開始されるのを制御する新しい規制メカニズムを明らかにしています.
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