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Deep-etch visualization of proteins involved in clathrin assembly
1Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110.
The Journal of Cell Biology
|September 1, 1988
Summary
Assembly protein 2 (AP-2) has a tripartite structure with appendages essential for clathrin polymerization. These appendages bind to clathrin
Area of Science:
- Molecular Cell Biology
- Structural Biology
- Biochemistry
Background:
- Clathrin-coated vesicles are crucial for intracellular trafficking.
- Assembly proteins (APs) are key components of these vesicles.
- The specific role of AP-2 in clathrin assembly was not fully understood.
Purpose of the Study:
- To elucidate the structure of AP-2.
- To determine the function of AP-2 in clathrin polymerization.
- To visualize the interaction between AP-2 and clathrin.
Main Methods:
- Purification of AP-2 from bovine brain clathrin-coated vesicles.
- Freeze-etch electron microscopy for structural analysis.
- Enzymatic treatment (elastase, uncoating ATPase) to probe protein function.
- Visualization of AP-2 binding to clathrin and vesicle membranes.
Main Results:
- AP-2 exhibits a tripartite structure with distinct appendages and a central mass.
- Appendages are crucial for promoting clathrin polymerization.
- AP-2 binds to the terminal domains of clathrin triskelions.
- AP-2 is linked to the vesicle membrane via short stalks.
Conclusions:
- AP-2's appendages are essential for its role in clathrin assembly.
- AP-2 likely acts as an adaptor between the clathrin coat and the membrane.
- The study provides structural insights into AP-2 function in coated vesicle formation.