Role of alpha-SNAP in promoting efficient neurotransmission at the crayfish neuromuscular junction.
In this manuscript, we address the role of the soluble N-ethylmaleimide sensitive factor attachment protein (alpha-SNAP) in synaptic transmission at the neuromuscular junction of the crayfish opener muscle. Immunochemical methods confirm the presence of alpha-SNAP in these preparations and show that it is concentrated in the synaptic areas. Microinjection and electrophysiological studies show that alpha-SNAP causes an increase in neurotransmitter release yet does not significantly affect the kinetics. More specific quantal analysis, using focal, macropatch, synaptic current recordings, shows that alpha-SNAP increases transmitter release by increasing the probability of exocytosis but not the number of potential release sites. These data demonstrate that the role of alpha-SNAP is to increase the efficiency of neurotransmission by increasing the probability that a stimulus will result in neurotransmitter release. What this suggests is that alpha-SNAP is critical for the formation and maintenance of a "ready release" pool of synaptic vesicles.
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T. H. Morgan School of Biological Science, University of Kentucky, Lexington 40506-0225, USA.
Southard
R C
RC
Chen
D
D
Whiteheart
S W
SW
Cooper
R L
RL
D000818:Animals; D003400:Astacoidea / Q000502:physiology*; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005455:Fluorescent Antibody Technique; D066298:In Vitro Techniques; D008565:Membrane Proteins / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D008845:Microinjections; D009132:Muscles / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D009154:Mutation / Q000502:physiology; D009469:Neuromuscular Junction / Q000187:drug effects / Q000502:physiology*; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D033921:Vesicular Transport Proteins
D002352:Carrier Proteins; D008565:Membrane Proteins; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins; D033921:Vesicular Transport Proteins