Tim23は,ミトコンドリア内膜と外膜を結びつけています.
Cell
|June 1, 2000
まとめ
ミトコンドリアのタンパク質トランスロカゼであるTim23は,2つの膜を横断し,外と内ミトコンドリアの膜を結ぶ. この新しい構造は,前駆体移転を促進することによって,タンパク質の輸入効率を高めます.
科学分野:
- ミトコンドリア生物学 ミトコンドリア生物学
- 膜タンパク質のトポロジーは,
- タンパク質の輸入機械
背景:
- Tim23はミトコンドリア前タンパク質トランスロカゼの重要な成分です.
- それは内部のミトコンドリア膜に固定され,膜間空間にドメインがあります.
- 膜間タンパク質の転送を調整するTim23の正確なトポロジーと機能は完全に理解されていません.
研究 の 目的:
- ミトコンドリア膜内のTim23の完全なトポロジーを解明する.
- Tim23の新型膜横断特性による機能的影響を調査する.
- Tim23が外側と内側のミトコンドリア膜を統合する方法を理解するために.
主な方法:
- 生物化学的および細胞生物学的なアプローチがTim23トポロジーを決定するために使用されました.
- ミトコンドリア表面におけるタンパク質曝露の分析.
- タンパク質の輸入効率を評価するための機能分析.
主要な成果:
- Tim23は新しいトポロジーを持ち,そのN端ドメインはミトコンドリア膜の外側の表面に露出しています.
- Tim23はミトコンドリア内膜と外膜の両方に広がっており,以前は説明されなかった特徴です.
- この二重膜統合は,外側と内側のミトコンドリア膜の間の直接的な接触を形成します.
結論:
- Tim23のユニークな2つの膜を網羅するトポロジーは,その機能にとって不可欠です.
- TIM23は,TOMとTIM23複合体を結びつける分子結合として機能します.
- この結合は,前体タンパク質の移転とミトコンドリアへのインポートの効率を大幅に高めます.
関連する概念動画
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01:19Translocation of Proteins into the Mitochondria
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Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
01:12Porin Insertion in the Outer Mitochondrial Membrane
Porins are beta-barrel proteins translocated to the mitochondrial outer membrane through the TOM complex into the intermembrane space. Porin precursors bind TIM chaperones within the intermembrane space and are guided to the Sorting and Assembly Machinery complex or SAM complex on the outer mitochondrial membrane.
Three models describe the assembly of porins by the SAM complex and their insertion into the outer membrane. Model 1 suggests that porins are assembled outside the SAM channel as the...
Three models describe the assembly of porins by the SAM complex and their insertion into the outer membrane. Model 1 suggests that porins are assembled outside the SAM channel as the...
01:34Protein Transport into the Inner Mitochondrial Membrane
Nuclear encoded mitochondrial precursors are imported to the inner membrane in a multistep process involving two separate translocons, TIM22 and TIM23. TIM23 is a cation-selective pore that remains closed by the N terminal segment of the protein. Negative charges on the TIM23 act as a receptor for the incoming precursor, pulling the positively charged matrix-targeting sequence for peptide insertion and translocation.
Transport of mitochondrial precursors across the TIM23 channel is driven by...
Transport of mitochondrial precursors across the TIM23 channel is driven by...
01:45Mitochondrial Membranes
A single mitochondrion is a bean-shaped organelle enclosed by a double-membrane system. The outer membrane of mitochondria is smooth and contains many porins - the integral membrane transporters. Porins enable free diffusion of ions and small uncharged molecules through the outer mitochondrial membrane but limit the transport of molecules larger than 5000 Daltons. Further, the outer mitochondrial membrane forms a unique structure called membrane contact sites with other subcellular organelles,...