ベータ-COPは,生体内では,エンドプラズマ網膜からゴルギ複合体への生合成膜輸送に不可欠です
R Pepperkok1, J Scheel, H Horstmann
1European Molecular Biology Laboratory, Heidelberg, Federal Republic of Germany.
Cell
|July 16, 1993
まとめ
コートタンパク質であるβ-COPを阻害すると,哺乳類の細胞内のウイルス性グリコタンパク質と内生タンパク質の輸送が阻害されます. これはβ-COPを証明しています.
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.
- タンパク質の密輸 タンパク質の密輸
背景:
- クラトリンで覆われていない膀は,細胞内輸送に不可欠です.
- ベータ-COP (コートタンパク質ベータ) は,これらの小胞の成分です.
- ベータ-COPの機能を理解することは,膜交通経路の解読の鍵です.
研究 の 目的:
- 生物合成膜交通におけるβ-COPのインビボの役割を調査する.
- ベータ-COP阻害によって影響を受けるタンパク質輸送の特定の段階を決定する.
主な方法:
- 哺乳類の細胞にβ-COPに対する抗体の微注射.
- 温度感受性膀性口炎ウイルスグリコタンパク質 (ts-O45-G) をモデル貨物として利用.
- 温度変化と細胞表面輸送アッセイを介してタンパク質の輸送と改変 (例えば,エンドグリコシダゼH抵抗) を分析する.
主要な成果:
- ベータ-COPに対する抗体は,ts-O45-Gの細胞表面への輸送を阻害した.
- 阻害は,エンドプラズマ網膜 (ER) と中間区間の段階では発生したが,トランス・ゴルギネットワークでは発生しなかった.
- Ts-O45-Gは,ER-Golgiの中間の管状構造に蓄積されている.
- 内生タンパク質の分泌とキャセプシンDの成熟も低下した.
結論:
- ベータ-COPは,哺乳類の細胞生物合成膜の伝達において重要な役割を果たします.
- ベータ-COPの阻害は,早期から中期の段階でタンパク質輸送を妨げます.
- これらの発見は,ベータ-COPが膀媒介による輸送における重要な機能のインビボ証拠を提供する.
関連する概念動画
00:59COP Coated Vesicles
Membrane-enclosed structures called vesicles transport proteins and lipids across the cell. The vesicles derive their cargo from the plasma membrane, Golgi, ER, or endosome. Coated vesicles are spherical, protein-coated carriers with a 50–100 nm diameter that mediate bidirectional transport between the ER and the Golgi. The distribution of proteins between the ER and Golgi complex is dynamic and is maintained by different coated vesicles. Their formation is driven by the assembly of different...
01:33Coat Assembly and GTPases
Vesicles incorporate different coat protein subunits in different cell locations, which changes the properties of the coat, such as the shape and geometry of the transport vesicles. Thus, vesicle coat proteins also play a significant role in cargo selection.
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
01:45ER Retrieval Pathway
In the secretory pathway, vesicles transport proteins from one cellular compartment to another in forward transport to deliver the protein to its correct location. Occasionally, misfolded proteins and incorrect proteins escape their original compartments, and a retrieval pathway is used to return the escaped proteins to their original compartment.
The ER uses many checkpoints to prevent the entry of incorrectly folded or a resident protein as cargo onto a transport vesicle. These mechanisms...
The ER uses many checkpoints to prevent the entry of incorrectly folded or a resident protein as cargo onto a transport vesicle. These mechanisms...
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...
01:26Transport Across the Golgi
While it is unclear how molecules move between adjacent Golgi cisternae, it is apparent that the molecules move from cis- cisterna, the entry face, to the trans- cisterna, the exit face. Experiments initially suggested vesicles that bud from one cisterna and fuse with the next cisterna to transport proteins between the cisternae. This vesicular transport model describes the Golgi apparatus as a relatively static structure with a unique enzyme composition in each cisterna. Molecules are...