Abstract
Whether glutamate is released rapidly, in an all-or-none manner, or more slowly, in a regulated manner, is a matter of debate. We analyzed the time course of excitatory postsynaptic currents (EPSCs) at glutamatergic neuromuscular junctions of Drosophila and found that the decay phase of EPSCs was protracted to a variable extent. The protraction was more pronounced in evoked and spontaneous quantal EPSCs than in action potential-evoked multiquantal EPSCs; reduced in quantal EPSCs from endophilin null mutants, which maintain release via kiss-and-run; and dependent on synaptotagmin isoform, calcium, and protein phosphorylation. Our data indicate that glutamate is released from individual synaptic vesicles for milliseconds through a fusion pore. Quantal glutamate discharge time course depends on presynaptic calcium inflow and the molecular composition of the release machinery.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Action Potentials / physiology
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Adaptor Proteins, Signal Transducing*
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Animals
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Calcium Signaling / genetics
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Calcium-Binding Proteins*
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Carrier Proteins / genetics
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Carrier Proteins / metabolism
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Drosophila melanogaster / cytology
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Drosophila melanogaster / metabolism*
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Excitatory Postsynaptic Potentials / physiology*
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Glutamic Acid / metabolism*
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Larva
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Membrane Fusion / physiology*
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Membrane Glycoproteins / genetics
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Membrane Glycoproteins / metabolism
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Nerve Tissue Proteins / genetics
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Nerve Tissue Proteins / metabolism
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Neuromuscular Junction / metabolism*
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Neuromuscular Junction / ultrastructure
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Phosphorylation
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Synaptic Membranes / metabolism
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Synaptic Membranes / ultrastructure
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Synaptic Transmission / physiology*
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Synaptic Vesicles / metabolism*
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Synaptic Vesicles / ultrastructure
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Synaptotagmins
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Time Factors
Substances
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Adaptor Proteins, Signal Transducing
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Calcium-Binding Proteins
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Carrier Proteins
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Membrane Glycoproteins
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Nerve Tissue Proteins
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Synaptotagmins
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Glutamic Acid