授与前の哺乳類のリボソームSRP·SRP受容体標的複合体の構造
Kan Kobayashi1, Ahmad Jomaa1, Jae Ho Lee2
1Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, Zurich CH-8093, Switzerland.
まとめ
信号認識粒子 (SRP) とSRP受容体 (SR) は,タンパク質をエンドプラズマ網膜に誘導するタンパク質複合体を形成する. この研究は この複合体の構造を明らかにし タンパク質の移転にどのように安定させるかを示しています
科学分野:
- 分子生物学
- 細胞生物学
- 構造生物学
背景:
- 信号認識粒子 (SRP) 経路は,タンパク質をエンドプラズマ網膜 (ER) にターゲティングするために不可欠です.
- SRPはリボソームから発生する新生ポリペプチドのシグナル配列に結合する.
- ER膜への送達には,SRP受容体 (SR) とその後のトランスロコンへの転送が含まれます.
研究 の 目的:
- 哺乳類のリボソーム-SRP-SR複合体の冷凍電子顕微鏡構造を決定する.
- トランスロコンに信号配列の移転を先行する形状を視覚化します.
- この複合体の安定化における真核特異性SRPとSRタンパク質の役割を解明する.
主な方法:
- SRPとSRで複合した哺乳類の翻訳リボソームの冷凍電子顕微鏡 (冷凍EM)
- GTPの水解率を調査する生化学的測定法
主要な成果:
- 凍結-EM構造はリボソーム-SRP-SR複合体の安定した構造を示しています.
- ユーカリオット固有のSRPとSRタンパク質は,SRPRNAの遠隔部位で大きなアセンブリを形成し,複合体を安定させます.
- 生化学的なデータは,この形状のSRP·SRのGTP水解が遅れていることを示している.
結論:
- 観察された構造は,ERへのタンパク質標的化メカニズムを洞察します.
- SRPとSRタンパク質による安定化は,シグナル配列の効率的な移転のための時間窓を作り出す可能性が高い.
- このメカニズムはタンパク質を ER膜に正確に挿入することを保証します.
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