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A possible docking and fusion particle for synaptic transmission
G Schiavo1, M J Gmachl, G Stenbeck
1Cellular Biochemistry and Biophysics Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
Nature
|December 14, 1995
Summary
Beta-SNAP, a brain protein, forms a fusion complex with synaptotagmin, linking membrane fusion to calcium signaling. This complex
Area of Science:
- Neurobiology
- Molecular Biology
- Cellular Neuroscience
Background:
- Proteins like NSF, alpha-SNAP, SNAREs, and synaptotagmin are involved in neurotransmitter release.
- A second SNAP isoform, beta-SNAP, is abundant in the brain, but its function is unknown.
- Synaptotagmin is a potential calcium sensor for exocytosis.
Purpose of the Study:
- To elucidate the role of beta-SNAP in the formation of the neurotransmitter release complex.
- To investigate how beta-SNAP interacts with other proteins in the exocytosis machinery.
- To understand the mechanism by which polyphosphoinositols affect transmitter release.
Main Methods:
- Co-expression and co-assembly studies of SNAP isoforms, NSF, and synaptotagmin.
- Binding assays to determine protein-protein interactions.
- Inhibition studies using polyphosphoinositols (InsP4, InsP5, InsP6) to assess their effect on complex assembly and function.
Main Results:
- Proteins cooperatively assemble into a docking and fusion complex.
- Beta-SNAP, but not alpha-SNAP, binds to synaptotagmin and recruits NSF.
- Polyphosphoinositols block beta-SNAP binding to synaptotagmin, inhibiting complex assembly and transmitter release.
Conclusions:
- Beta-SNAP acts as a crucial link between the calcium sensor synaptotagmin and the membrane fusion machinery.
- The beta-SNAP/synaptotagmin interaction is essential for recruiting NSF and forming the functional fusion complex.
- Polyphosphoinositols inhibit neurotransmitter release by disrupting the beta-SNAP/synaptotagmin interaction.