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精製された酵母Sec複合体と膜のないKar2pによるタンパク質輸送
K E Matlack1, K Plath, B Misselwitz
1Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
Science (New York, N.Y.)
|August 15, 1997
まとめ
酵母体内プラズマ網膜のタンパク質転位は,Sec複合体とKar2タンパク質を使用しています. Sec複合体は,Kar2pとATPの水解によって動かし,そのチャネルを通して基板の移動を促進します.
科学分野:
- 細胞生物学 細胞生物学
- 分子生物学は分子生物学である.
- タンパク質の輸送
背景:
- 細胞機能には,エンドプラズマ網膜 (ER) 膜を横断した翻訳後のタンパク質の転位が極めて重要です.
- 酵母におけるこのプロセスは,7つの成分からなるSec複合体と,光内タンパク質Kar2 (Kar2p) を含む.
研究 の 目的:
- Sec複合体とKar2pによるタンパク質転位のメカニズムを解明する.
- Sec複合チャネルを通る基質の移動におけるKar2pとATPの水解の役割を調査する.
主な方法:
- 洗浄剤溶液で再構成された浄化されたSec複合体を使用しました.
- Kar2pとATPへの反応として,基板結合と転位をモニターした.
- 脂質二層がない場合の転位を調査した.
主要な成果:
- タンパク質転位基板は,シグナル配列に依存した方法でSec複合体の細胞溶面と結合する.
- Kar2pは,光面と相互作用し,ATPを水分解して基質の動きを誘導する.
- 基板の転位は,脂質二重層から独立してSec複合体によって形成されたチャネルを通じて発生します.
結論:
- Sec複合体は,ER膜を横断してタンパク質の転位を促進するチャネルを形成する.
- Kar2pはモーターとして作用し,ATPの水解を利用して,Sec複合チャネルを通して基質を積極的に移動させます.
- 脂質二層は,Sec.複合体の転位チャネル機能に不可欠ではない.
関連する概念動画
01:33Overview of Secretory Vesicles
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Various proteins regulate the aggregation of molecules inside the secretory vesicles. Chromogranins...
01:45Overview of Protein Sorting and Transport
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01:34Nuclear Protein Sorting
Nuclear protein sorting is the selective trafficking of histones, polymerases, gene regulatory proteins into the nucleus and exporting RNAs and ribosomes to the cytosol. It is a tightly controlled process that regulates gene expression within a cell.
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Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
01:20Cotranslational 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...
01:27Post-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...
01:28Protein 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.