双孔トランスロカゼによってミトコンドリア内膜にタンパク質を挿入する
Peter Rehling1, Kirstin Model, Katrin Brandner
1Institut für Biochemie und Molekularbiologie, Universität Freiburg, Hermann-Herder-Strasse 7, D-79104 Freiburg, Germany.
まとめ
TIM22複合体は,膜ポテンシャル (Deltapsi) を使用してミトコンドリア内膜にタンパク質を挿入します. この双孔トランスロカゼは,効率的なタンパク質挿入のために,デルタプシとシグナルペプチドを含む2つのエネルギー依存のステップを使用します.
科学分野:
- ミトコンドリア生物学 ミトコンドリア生物学
- 蛋白質の転位によるタンパク質転位です.
- 膜バイオフィジックス
背景:
- ミトコンドリアは,内膜を通して多数のタンパク質を輸入する.
- 膜ポテンシャル (Deltapsi) は,このプロセスの主要なエネルギー源です.
- マルチスパンディングタンパク質挿入の仕組みを理解することは極めて重要です.
研究 の 目的:
- ミトコンドリア内膜にタンパク質が挿入されるメカニズムを解明する.
- タンパク質転位におけるTIM22複合体の機能を特徴付ける.
- タンパク質挿入における膜ポテンシャルの役割を調査する.
主な方法:
- TIM22複合体の浄化について.
- タンパク質の挿入を研究するための生化学的分析.
- 3段階の挿入プロセスの分析.
- デルタプシとシグナルペプチドの役割を調査する.
主要な成果:
- 双孔トランスロカゼであるTIM22複合体は,タンパク質の挿入を媒介する.
- タンパク質の挿入は,3段階のプロセスで起こります.
- デルタプシは,タンパク質のドッキングと,その後の膜挿入を駆動する.
- 双胞胎孔複合体とシグナルペプチドの連携した作用は,効率的な挿入を保証します.
結論:
- ミトコンドリア内膜へのタンパク質の挿入は,複雑で多段階のプロセスです.
- TIM22複合体は,デルタプシを2つの電圧依存のステップで利用する双孔トランスロカゼとして機能します.
- トランスロカゼと内部信号の協調した作用は,完全な膜挿入を促します.
関連する概念動画
Protein 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...
Cotranslational Protein Translocation
Translocation of proteins across membranes is an ancient process that occurs even in bacteria and archaebacteria. In fact, the components of the translocation machinery are still conserved between prokaryotes and eukaryotes.
Sec61 channel partners for cotranslational translocation
During cotranslational translocation, the Sec61 channel partners with the signal recognition particle (SRP), the signal recognition particle receptor (SR), and the ribosomes to transport the nascent polypeptide chain...
Sec61 channel partners for cotranslational translocation
During cotranslational translocation, the Sec61 channel partners with the signal recognition particle (SRP), the signal recognition particle receptor (SR), and the ribosomes to transport the nascent polypeptide chain...
Insertion of Single-pass Transmembrane Proteins in the RER
Integral membrane proteins are proteins adhered to the lipid bilayer of a cell organelle or membrane. They can be of two types: transmembrane integral proteins that span the lipid bilayer and monotopic proteins that are attached to either side of the membrane but do not pass through it.
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
Insertion of Multi-pass Transmembrane Proteins in the RER
The rough ER membrane synthesizes, assembles, and embeds transmembrane proteins in diverse topologies. These proteins function as transporters or channels and can remain in the ER membrane or are sent to the Golgi complex, lysosome, and cell membrane.
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
Post-translational Translocation of Proteins to the RER
A sizable fraction of proteins destined for ER are first synthesized in the cell cytosol and then transported across the ER membrane–a process called post-translational translocation. Similar to cotranslationally translocated proteins, these proteins also use the Sec translocon complex to enter the ER lumen.
Targeting proteins to the ER
Hsp40 and Hsp70 chaperone molecules bind the translated proteins in the cytosol to prevent their folding. The chaperone binding helps to keep the signal...
Targeting proteins to the ER
Hsp40 and Hsp70 chaperone molecules bind the translated proteins in the cytosol to prevent their folding. The chaperone binding helps to keep the signal...
Protein Translocation Machinery on the ER Membrane
The translocon complex situated on the ER membrane is the main gateway for the protein secretory pathway. It facilitates the transport of nascent peptides into the ER lumen and their insertion into the ER membrane.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.


