Postfusional control of quantal current shape.
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.
Pawlu
Christian
C
Physiologisches Institut, Universität Freiburg, D-79104 Freiburg, Germany.
DiAntonio
Aaron
A
Heckmann
Manfred
M
D000200:Action Potentials / Q000502:physiology; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D020013:Calcium Signaling / Q000235:genetics; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000166:cytology / Q000378:metabolism*; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology*; D018698:Glutamic Acid / Q000378:metabolism*; D007814:Larva; D008561:Membrane Fusion / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009469:Neuromuscular Junction / Q000378:metabolism* / Q000648:ultrastructure; D010766:Phosphorylation; D013570:Synaptic Membranes / Q000378:metabolism / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology*; D013572:Synaptic Vesicles / Q000378:metabolism* / Q000648:ultrastructure; D050857:Synaptotagmins; D013997:Time Factors
D048868:Adaptor Proteins, Signal Transducing; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D050857:Synaptotagmins; D018698:Glutamic Acid