Related Experiment Video
Updated: Jun 27, 2026
12:15
In Vitro Polymerization of F-actin on Early Endosomes
Published on: August 28, 2017
Caveolin-1 activates Rab5 and enhances endocytosis through direct interaction
Makoto Hagiwara1, Yukiya Shirai, Ryosuke Nomura
1Department of Agricultural Chemistry, Graduate School of Agriculture, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan.
Biochemical and Biophysical Research Communications
|November 18, 2008
Summary
Caveolin-1 protein directly interacts with Rab5, a key molecule in cellular transport. This interaction is crucial for controlling Rab5 activity during caveolae-mediated endocytosis.
Area of Science:
- Cell Biology
- Molecular Biology
- Endocytosis Research
Background:
- Caveolin-1 is a protein essential for caveolae formation and function.
- Caveolae-mediated endocytosis is a vital cellular process for internalizing molecules.
- The precise molecular mechanisms governing caveolae-mediated endocytosis remain incompletely understood.
Purpose of the Study:
- To elucidate the physiological role of the Rab5-caveolin-1 interaction in caveolae-mediated endocytosis.
- To identify the specific domains of caveolin-1 involved in binding Rab5.
- To determine if caveolin-1 influences Rab5 activity.
Main Methods:
- Co-fractionation analysis to detect Rab5 in caveolae-enriched fractions.
- Direct binding assays to confirm Rab5-caveolin-1 interaction.
- Site-directed mutagenesis to identify Rab5 binding domains on caveolin-1.
- GST-pull down assays and GTP-loading assays in Cos-1 cells to assess Rab5 activity.
Main Results:
- Rab5 was detected in caveolae-enriched fractions and shown to directly bind caveolin-1.
- Specific binding sites for Rab5 were identified within the scaffold, transmembrane, and C-terminus domains of caveolin-1.
- The Rab5 binding domain of caveolin-1 was essential for cholera toxin B (CTXB) uptake.
- Overexpression of the caveolin-1 Rab5 binding domain enhanced Rab5-GTP levels, indicating increased Rab5 activity.
Conclusions:
- Caveolin-1 directly interacts with Rab5, playing a significant role in caveolae-mediated endocytosis.
- The interaction between caveolin-1 and Rab5 is critical for regulating Rab5 activity.
- These findings provide new insights into the molecular machinery governing endocytosis via caveolae.
More Related Videos
12:40Visualizing Clathrin-mediated Endocytosis of G Protein-coupled Receptors at Single-event Resolution via TIRF Microscopy
Published on: October 20, 2014
10:02Applications of pHluorin for Quantitative, Kinetic and High-throughput Analysis of Endocytosis in Budding Yeast
Published on: October 23, 2016
Related Concept Videos
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.
01:14Rab 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...
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...
01:33Coat 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...
01:28The Early Endosome: Endocytosis of Transferrin
Essential proteins such as insulin or low-density lipoprotein (LDL) and micronutrients such as iron enter a eukaryotic cell through receptor-mediated endocytosis. Subsequently, the early endosomes fuse with the vesicles containing such receptor-ligand complexes and play a vital role in sorting the incoming ligands and receptors. While the ligands are either degraded inside the vesicle or released into the cytosol, their receptors are returned to the plasma membrane for further rounds of...
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...