Faculty Research 1990 - 1999
Distinct requirements for evoked and spontaneous release of neurotransmitter are revealed by mutations in the Drosophila gene neuronal-synaptobrevin.
Document Type
Article
Publication Date
1998
Keywords
Drosophila, Female, Male, Membrane-Proteins, Mutation, Neuromuscular-Junction, Neurons, Neurotransmitters, Paralysis, Synapses
First Page
2028
Last Page
2039
JAX Source
J Neurosci 1998 Mar; 18(6):2028-39.
Abstract
Two modes of vesicular release of transmitter occur at a synapse: spontaneous release in the absence of a stimulus and evoked release that is triggered by Ca2+ influx. These modes often have been presumed to represent the same exocytotic apparatus functioning at different rates in different Ca2+ concentrations. To investigate the mechanism of transmitter release, we have examined the role of synaptobrevin/VAMP, a protein involved in vesicular docking and/or fusion. We generated a series of mutations, including null mutations, in neuronal-synaptobrevin (n-syb), the neuronally expressed synaptobrevin gene in Drosophila. Mutant embryos completely lacking n-syb form morphologically normal neuromuscular junctions. Electrophysiological recordings from the neuromuscular junction of these mutants reveal that the excitatory synaptic current evoked by stimulation of the motor neuron is abolished entirely. However, spontaneous release of quanta from these terminals persists, although its rate is reduced by 75%. Thus, at least a portion of the spontaneous "minis" that are seen at the synapse can be generated by a protein complex that is distinct from that required for an evoked synaptic response.
Recommended Citation
Deitcher DL,
Ueda A,
Stewart BA,
Burgess RW,
Kidokoro Y,
Schwarz TL.
Distinct requirements for evoked and spontaneous release of neurotransmitter are revealed by mutations in the Drosophila gene neuronal-synaptobrevin. J Neurosci 1998 Mar; 18(6):2028-39.