Role of alpha-SNAP in promoting efficient neurotransmission at the crayfish neuromuscular junction

J Neurophysiol. 1999 Dec;82(6):3406-16. doi: 10.1152/jn.1999.82.6.3406.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Astacoidea / physiology*
  • Blotting, Western
  • Carrier Proteins / genetics
  • Carrier Proteins / pharmacology
  • Carrier Proteins / physiology*
  • Excitatory Postsynaptic Potentials / drug effects
  • Excitatory Postsynaptic Potentials / physiology
  • Fluorescent Antibody Technique
  • In Vitro Techniques
  • Membrane Proteins / genetics
  • Membrane Proteins / pharmacology
  • Membrane Proteins / physiology*
  • Microinjections
  • Muscles / cytology
  • Muscles / drug effects
  • Muscles / physiology
  • Mutation / physiology
  • Neuromuscular Junction / drug effects
  • Neuromuscular Junction / physiology*
  • Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins
  • Synaptic Transmission / drug effects
  • Synaptic Transmission / physiology*
  • Vesicular Transport Proteins*


  • Carrier Proteins
  • Membrane Proteins
  • Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins
  • Vesicular Transport Proteins