関連する実験動画
Updated: Nov 17, 2025
05:52
Reconstitution of Msp1 Extraction Activity with Fully Purified Components
Published on: August 10, 2021
2.8K
ミトコンドリアタンパク質合成のメカニズム
Yuzuru Itoh1,2, Juni Andréll1,2, Austin Choi3
1Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 17165 Solna, Stockholm, Sweden. abarrientos@med.miami.edu brendan.battersby@helsinki.fi amunts@scilifelab.se.
Science (New York, N.Y.)
|February 19, 2021
まとめ
人間のミトリボソーム (mtRs) は,OXA1L挿入酵素を3つの部位で結合させ,新たに合成されたタンパク質のコトランスレーション膜挿入を可能にします. ミトコンドリア内膜へのタンパク質の供給を容易にする.
科学分野:
- 細胞生物学
- 分子生物学
- 構造生物学
背景:
- ミトコンドリアのリボソーム (ミトリボソーム) は,ミトコンドリア内のタンパク質の合成に不可欠です.
- これらのリボソームはしばしばミトコンドリア内膜と関連付けられ,新たに合成された膜タンパク質を挿入するのに役立ちます.
- このコトランスレーション性挿入の正確なメカニズム,特にOXA1Lのような挿入酵素の役割は,まだ完全に理解されていません.
研究 の 目的:
- OXA1L挿入酵素とのヒトミトリボソームの相互作用の構造的基礎を解明する.
- この相互作用が,ミトコンドリアタンパク質の共翻訳性膜挿入をどのように促進するのかを理解する.
主な方法:
- クリオ電子顕微鏡 (cryo-EM) を用いて,ヒトのミトリボソームがOXA1Lに結合する構造を決定した.
- これらの構造の分析は 異なる接触部位と形状の変化を明らかにした.
主要な成果:
- ミトリボソームとOXA1Lの3つの異なる接触部位が特定されました.
- OXA1L結合は,特にmL45タンパク質を含むミトリボソームの大型サブユニットにおける構造変化を誘導する.
- mL45の折り畳みは,出口トンネル内の収縮部位を作り,新生ポリペプチドヘリックス形成を制限し,タンパク質アクセシビリティのギャップを作成します.
- この構造的配置は,新生ポリペプチドの膜への供給を容易にする.
結論:
- この研究は,ミトリボソームとOXA1Lがタンパク質合成と膜挿入を組み合わせるための詳細な構造的メカニズムを示しています.
- これはミトコンドリアタンパク質の 生成と膜統合に関する 根本的な洞察を提供します
関連する概念動画
01:19Translocation of Proteins into the Mitochondria
10.0K
Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
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,...
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,...
10.0K
01:39Mitochondrial Protein Sorting
5.2K
Mitochondria are double-membrane organelles of the eukaryotes involved in cellular metabolism, signaling, ATP synthesis, and programmed cell death. Each of these processes requires specific proteins and enzymes that must be correctly sorted to the right mitochondrial subcompartment for the proper functioning of the organelle.
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
5.2K
01:12Porin Insertion in the Outer Mitochondrial Membrane
4.0K
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...
4.0K
01:34Protein Transport into the Inner Mitochondrial Membrane
4.4K
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...
4.4K
01:37Energy to Drive Translocation
2.4K
Mitochondrial protein import is powered by two distinct energy sources: ATP hydrolysis and electrochemical potential across the inner membrane. Newly synthesized precursors are bound by cytosolic chaperones of the Hsp70 family, which guide them to the import receptors on the mitochondrial surface. Utilizing the energy of ATP hydrolysis, Hsp70 chaperones transfer these precursors to the TOM receptors on the mitochondrial outer membrane.
Generally, polypeptides are unfolded by two distinct...
Generally, polypeptides are unfolded by two distinct...
2.4K
01:21Structure of Porins
3.6K
Mitochondria, chloroplasts, and gram-negative bacteria have transmembrane, beta-barrel proteins called porins to mediate the free diffusion of ions and metabolites across the membrane. Mitochondrial porin precursors contain conserved amino acid sequences called beta signals at their C-terminal. Beta signals have a motif of PoXGXXHyXHy (Po-Polar, X-Any amino acid, G-Glycine, Hy-LargeHydrophobic), which are crucial for precursor recognition to initiate precursor assembly. Beta-barrel...
3.6K