関連する実験動画
Updated: Jun 5, 2026
12:13
Single-Molecule Imaging of Nuclear Transport
Published on: June 10, 2010
COPIIサブユニットSec24pの複数の貨物結合部位は,様々な膜タンパク質を輸送ベジクルに捕獲することを保証します
Elizabeth A Miller1, Traude H Beilharz, Per N Malkus
1Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
Cell
|August 28, 2003
まとめ
膀輸送に不可欠なタンパク質であるSec24pは,複数の結合部位を使用して,多様な貨物分子を選択します. これらのサイトは,異なる分類シグナルを独立して認識し,効率的なタンパク質包装を確保します.
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.
- タンパク質の密輸 タンパク質の密輸
背景:
- COPII (コート・プロテイン・コンプレックスII) 機構は,エンドプラズマ網膜 (ER) からゴルジ装置へのタンパク質輸送を媒介する.
- Sec24pはCOPIIの重要なサブユニットで,貨物分子を選択してER由来ベシクルに包装する責任を負う.
- Sec24pの貨物認識メカニズムを理解することは,細胞内トラフィックの経路を解読するために不可欠です.
研究 の 目的:
- COPIIサブユニットの貨物選択メカニズムを特徴づけるためにSec24p.
- 貨物結合に関与するSec24p上の特定の相互作用部位を特定し,分析する.
- Sec24pが様々な貨物分子を認識し,パッケージ化する方法を解明する.
主な方法:
- 貨物相互作用のための重要な残留物を特定するためにSec24pのサイト指向型変異.
- 変異したSec24pの変種を用いた貨物包装効率の分析.
- 貨物の選択におけるSec24pとその同類であるLst1pの比較分析.
- 異なるSNAREタンパク質のためのSec24p上の異なる結合ドメインの識別.
主要な成果:
- v-SNARE Bet1pを認識するSec24pの特定のサイトが特定され,ここで突然変異が様々な貨物分子の包装を混乱させた.
- これらの変異によって影響を受けた貨物タンパク質には,共通の分類信号が欠け,同様の信号でさえ,均一に影響を受けなかった.
- 特定されたサイトは,Sec24pの荷物のサブセットをパッケージするSec24pの同型Lst1pに保存されています.
- さらに別の変異により,Sec24pに異なる貨物結合ドメインが定義され,それは特にSNARE Sec22pと相互作用する.
結論:
- Sec24pは,複数の独立した貨物結合ドメインを有しています.
- これらのドメインは,さまざまな種類の貨物分類信号の認識を可能にします.
- この多ドメイン構造は,様々なタンパク質をCOPIIベシクルに効率的かつ特異的に包装することを容易にする.
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...
01:45Vesicular Tubular Clusters
After budding out from the ER membrane, some COPII vesicles lose their coat and fuse with one another to form larger vesicles and interconnected tubules called vesicular tubular clusters or VTCs. These clusters constitute a compartment at the ER-Golgi interface known as ERGIC (Endoplasmic Reticulum Golgi Intermediate Compartment). The ERGIC is a mobile membrane-bound cargo transport system that sorts proteins secreted from ER and delivers them to the Golgi.
With the help of motor proteins such...
With the help of motor proteins such...
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...
01:12Clathrin Coated Vesicles
Clathrin-coated vesicles use endocytosis to transport receptors and lysosomal hydrolases from the Golgi to the lysosome in the late secretory pathway. Clathrin-mediated endocytosis was the first described endocytic process, and Clathrin-coated vesicles remain one of the most well-studied transport vesicles. The molecular machinery that generates clathrin-coated vesicles comprises over 50 proteins that precisely coordinate vesicle formation. Cell surface receptors concentrated in indented sites...
01:25Rab Cascades
Rab GTPases act in a regulated cascade during membrane fusion, helping the lipid bilayers mix. The Rab family of proteins are active when bound to GTP, and inactive when bound to GDP. Hence, they act as guanine nucleotide-dependent molecular switches. Rab-GTP recognizes and binds to long or short-range tethering proteins to capture the target vesicle. These tethers coordinate with SNAREs on the vesicle and the target membrane to assemble the trans SNARE complex that locks the mixing bilayers.