To investigate the molecular interactions of synaptophysin I and vesicle-associated membrane protein 2 (VAMP2)/synaptobrevin II during exocytosis, we have used time-lapse videomicroscopy to measure fluorescence resonance energy transfer in live neurons. For this purpose, fluorescent protein variants fused to synaptophysin I or VAMP2 were expressed in rat hippocampal neurons. We show that synaptophysin I and VAMP2 form both homo- and hetero-oligomers on the synaptic vesicle membrane. When exocytosis is stimulated with alpha-latrotoxin, VAMP2 dissociates from synaptophysin I even in the absence of appreciable exocytosis, whereas synaptophysin I oligomers disassemble only upon incorporation of the vesicle with the plasma membrane. We propose that synaptophysin I has multiple roles in neurotransmitter release, regulating VAMP2 availability for the soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex and possibly participating in the late steps of exocytosis.

Fluorescence resonance energy transfer detection of synaptophysin I and vesicle-associated membrane protein 2 interactions during exocytosis from single live synapses.

Pennuto, Maria;
2002-01-01

Abstract

To investigate the molecular interactions of synaptophysin I and vesicle-associated membrane protein 2 (VAMP2)/synaptobrevin II during exocytosis, we have used time-lapse videomicroscopy to measure fluorescence resonance energy transfer in live neurons. For this purpose, fluorescent protein variants fused to synaptophysin I or VAMP2 were expressed in rat hippocampal neurons. We show that synaptophysin I and VAMP2 form both homo- and hetero-oligomers on the synaptic vesicle membrane. When exocytosis is stimulated with alpha-latrotoxin, VAMP2 dissociates from synaptophysin I even in the absence of appreciable exocytosis, whereas synaptophysin I oligomers disassemble only upon incorporation of the vesicle with the plasma membrane. We propose that synaptophysin I has multiple roles in neurotransmitter release, regulating VAMP2 availability for the soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex and possibly participating in the late steps of exocytosis.
2002
8
Pennuto, Maria; Dunlap, D; Contestabile, A; Benfenati, F; Valtorta, F.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/98257
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