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TRAPP stably associates with the Golgi and is required for vesicle docking
J Barrowman1, M Sacher, S Ferro-Novick
1Howard Hughes Medical Institute, Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06519, USA.
The EMBO Journal
|March 4, 2000
Summary
Bet3p, a TRAPP complex component, is essential for vesicle docking to Golgi membranes. Its stable Golgi localization is crucial for this process, as demonstrated by in vitro binding assays.
Area of Science:
- Cell biology
- Protein complex function
- Membrane trafficking
Background:
- The TRAPP complex is involved in endoplasmic reticulum (ER)-Golgi transport.
- Bet3p is a component of the TRAPP complex and is localized to Golgi membranes.
- The precise role of TRAPP and Bet3p in vesicle docking remains unclear.
Purpose of the Study:
- To investigate the role of Bet3p and the TRAPP complex in vesicle docking at the Golgi.
- To determine the localization dynamics of Bet3p and TRAPP during ER-Golgi transport.
Main Methods:
- Immunofluorescence microscopy to assess protein localization.
- In vitro vesicle binding assays using Golgi membranes and cytosol.
- Analysis of protein association with Golgi membranes under blocked anterograde traffic.
Main Results:
- Bet3p exclusively localizes to Golgi membranes, unlike other SNAREs.
- Bet3p and TRAPP subunits remain associated with the Golgi even when anterograde traffic is blocked.
- Transport vesicles failed to bind to Golgi membranes in vitro without Bet3p.
- Bet3p-containing cytosol restored vesicle binding to Golgi membranes.
Conclusions:
- TRAPP, via Bet3p, stably associates with the Golgi.
- Bet3p is indispensable for the docking of transport vesicles to the Golgi.
- Persistent TRAPP localization at the Golgi is critical for its function in vesicle docking.