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VAP-A binds promiscuously to both v- and tSNAREs
1Programme in Cell Biology, Department of Biochemistry, Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, Ontario, M5G 1X8, Canada.
Biochemical and Biophysical Research Communications
|August 21, 2001
Summary
Vesicle-associated membrane protein-associated protein A (VAP-A) binds multiple SNAREs, suggesting a broad role in ER/Golgi vesicle transport. This protein likely facilitates general vesicle traffic rather than regulating specific VAMPs.
Area of Science:
- Cell Biology
- Molecular Biology
- Protein Interactions
Background:
- Proteins interacting with SNAREs (soluble NSF attachment protein receptors) can modulate their function.
- Vesicle-associated membrane protein-associated protein A (VAP-A), a mammalian homolog of Aplysia VAP-33, has been proposed to be involved in vesicle targeting.
Purpose of the Study:
- To investigate the cellular localization and binding partners of VAP-A.
- To determine the role of VAP-A in SNARE-mediated vesicle transport.
Main Methods:
- Immunofluorescence microscopy to determine VAP-A localization in COS-7 cells.
- In vitro binding assays to identify SNAREs and fusion-related proteins interacting with VAP-A.
- Analysis of N- and C-terminal domains for VAMP-binding and VAP-dimerization.
Main Results:
- VAP-A is widely expressed and resides in the ER/Golgi intermediate compartment in COS-7 cells.
- Both N- and C-terminal domains of VAP-A are essential for VAMP-binding and VAP-dimerization.
- VAP-A binds to a diverse array of SNAREs and fusion proteins, including syntaxin 1A, rbet1, rsec22, alphaSNAP, and NSF.
Conclusions:
- VAP-A's broad binding profile suggests it is not a specific VAMP regulator.
- VAP-A likely plays a general role in SNARE-mediated vesicle traffic between the ER and Golgi in nonpolarized cells.