Synaptotagmin modulation of fusion pore kinetics in regulated exocytosis of dense-core vesicles
Journal
Science
Journal Volume
294
Journal Issue
5544
Date Issued
2001-11-02
Author(s)
Abstract
In the exocytosis of neurotransmitter, fusion pore opening represents the first instant of fluid contact between the vesicle lumen and extracellular space. The existence of the fusion pore has been established by electrical measurements, but its molecular composition is unknown. The possibility that synaptotagmin regulates fusion pores was investigated with amperometry to monitor exocytosis of single dense-core vesicles. Overexpression of synaptotagmin I prolonged the time from fusion pore opening to dilation, whereas synaptotagmin IV shortened this time. Both synaptotagmin isoforms reduced norepinephrine flux through open fusion pores. Thus, synaptotagmin interacts with fusion pores, possibly by associating with a core complex of membrane proteins and/or lipid.
Other Subjects
Biological membranes; Fluids; Lipids; Proteins; Neurotransmitters; Neurology; synaptotagmin; biochemistry; amperometry; article; cell transport; cell vacuole; chemical composition; electric conductivity; exocytosis; extracellular space; gene overexpression; kinetics; measurement; neurotransmission; nonhuman; porosity; priority journal; Animals; Calcium; Calcium Channels, P-Type; Calcium Channels, Q-Type; Calcium-Binding Proteins; Cell Membrane Structures; Chromogranins; Electrophysiology; Exocytosis; Kinetics; Membrane Fusion; Membrane Glycoproteins; Membrane Potentials; Nerve Tissue Proteins; Neurotransmitter Agents; Norepinephrine; PC12 Cells; Protein Isoforms; Rats; Recombinant Fusion Proteins; Secretory Vesicles; Synaptic Transmission; Synaptic Vesicles; Synaptotagmin I; Synaptotagmins
Type
journal article