タンパク質転位の開始時のSecYチャネルの構造
Eunyong Park1, Jean-François Ménétret2, James C Gumbart3
1Department of Cell Biology and Howard Hughes Medical Institute, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA.
Nature
|October 25, 2013
まとめ
リボソーム結合ではない新生ポリペプチド鎖は,タンパク質転位の間にSecYチャネルを開く. これは,硬い身体の動きと信号配列の横のゲート挿入を含む.
科学分野:
- 分子生物学は分子生物学である.
- 構造生物学 構造生物学とは
- バイオケミストリー バイオケミストリー
背景:
- 分泌タンパク質は,膜転位のためにタンパク質伝導チャネル (SecY/Sec61複合体) に入るために信号配列を使用します.
- 非アクティブなSecYチャネルには,プラグドメインとサイドゲートを持つ砂時計孔があります.
研究 の 目的:
- タンパク質転位時のSecYチャネル開閉のメカニズムを解明する.
- 早期移転中介企業の構造的基盤を決定する.
主な方法:
- 低温電子顕微鏡 (cryo-EM) を使用して,無活性および活性リボソームチャネル複合体の構造を決定しました.
- 構造は,原生生物および真核生物の源からの非翻訳および翻訳リボソーム-SecY複合体の両方のために分析されました.
主要な成果:
- リボソーム結合だけでは,閉じたSecYチャネルに最小限の変化を引き起こす.
- 新生ポリペプチド鎖,特に信号配列は,チャンネルを積極的に開きます.
- チャネルの開口には,SecY半分の硬いボディの動きと,ポリペプチドループの横のゲートへの挿入が含まれています.
結論:
- リボソームではなく,新生鎖がSecYチャネル開通の主要なトリガーです.
- 早期の転位には,ポリペプチドループ形成と信号配列の横のゲートへのインターキャレーションが含まれます.
関連する概念動画
Cotranslational Protein Translocation
8.4K
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...
8.4K
Insertion of Single-pass Transmembrane Proteins in the RER
13.1K
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...
13.1K
Protein Translocation Machinery on the ER Membrane
5.6K
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...
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...
5.6K
Post-translational Translocation of Proteins to the RER
5.7K
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...
5.7K
Bacterial Translocation and Protein Secretion
1.2K
Bacterial protein secretion involves translocation systems to ensure proteins reach their designated locations, including the plasma membrane, periplasm, outer membrane, or the external environment. These translocation systems are vital for bacterial physiology, supporting processes like membrane assembly, enzymatic activity in the periplasm, and interactions with the external environment. The division of labor between Sec and Tat pathways ensures efficiency in handling proteins with diverse...
1.2K
Directing Proteins to the Rough Endoplasmic Reticulum
12.1K
The organelle-specific signaling sequences direct proteins synthesized in the cytosol to their final destination like ER, mitochondria, peroxisomes, etc. Some of the proteins directed to ER are then trafficked via vesicles to other organelles within the cell or the extracellular environment through the Golgi complex. For example, the rough ER synthesizes soluble proteins for transportation to the lysosomes or secretion out of the cell. It can also synthesize transmembrane proteins that can...
12.1K


