Related Experiment Video
Updated: May 25, 2026
12:15
In Vitro Polymerization of F-actin on Early Endosomes
Published on: August 28, 2017
ArfGAP1 promotes COPI vesicle formation by facilitating coatomer polymerization
Yoko Shiba1, Ruibai Luo1, Jenny E Hinshaw2
1Laboratory of Cellular and Molecular Biology; National Cancer Institute, Bethesda, MD USA.
Cellular Logistics
|January 27, 2012
Summary
ArfGAP1 promotes COPI vesicle formation and membrane traffic. This study resolves controversy by showing ArfGAP1 aids coatomer assembly into COPI vesicles, supporting its role in cellular transport.
Area of Science:
- Cell Biology
- Molecular Biology
- Membrane Trafficking
Background:
- The function of ArfGAP1 in COPI vesicle biogenesis is debated, with conflicting results from different experimental systems.
- Some studies suggest ArfGAP1 promotes vesicle formation, while others indicate it acts as an uncoating factor inhibiting formation.
Purpose of the Study:
- To resolve the controversy surrounding ArfGAP1's role in COPI vesicle biogenesis.
- To investigate ArfGAP1's function using both in vitro model membranes and in vivo systems.
Main Methods:
- Re-examination of ArfGAP1's effect on large unilamellar vesicles (LUVs).
- Analysis of coatomer self-assembly with ArfGAP1 and cargo peptides.
- In vivo studies involving ArfGAP1 overexpression and COPI cargo trafficking.
Main Results:
- ArfGAP1 enhanced coatomer-induced deformation of LUVs.
- ArfGAP1 facilitated coatomer self-assembly into spherical structures, similar to clathrin.
- In vivo, ArfGAP1 overexpression led to vesicle accumulation and maintained COPI cargo trafficking.
Conclusions:
- Data support a model where ArfGAP1 promotes COPI vesicle formation and membrane traffic.
- ArfGAP1 plays a role in the assembly of coatomer into COPI structures.
- This study clarifies ArfGAP1's function in vesicular transport.
Related Concept Videos
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...
01:32Pinching-off of Coated Vesicles
Vesicle budding is orchestrated by distinct cytosolic proteins such as adaptor proteins, coat proteins, and GTPases. To initiate vesicle budding, membrane-bending proteins containing crescent-shaped BAR domains bind to the lipid heads in the bilayer and distort the membrane to form a protein-coated vesicle bud. Adaptors proteins such as AP2 for clathrin-coated vesicles can nucleate on the deformed membrane. Finally, coat proteins such as clathrin or COPI and COPII assemble into a coat forming...
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...
01:25Rab 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.
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...
01:14Rab Proteins
Rab proteins constitute the largest family of monomeric GTPases, of which 70 members are present in humans. Rab proteins and their effectors regulate consecutive stages of vesicle transport such as vesicle transport, docking, and fusion to the correct recipient membrane.
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...