[Neuromuscular synapse: molecular mechanisms of acetylcholine vesicular exocytosis].
The transmission of excitation from motor neurones to muscle fibers at the neuromuscular junction is made through liberation of acetylcholine. This is concentrated into vesicles according to an exchange with H(+) ions. Increase of intracellular calcium concentration leads some vesicles to mobilise and target with the neuron plasma membrane, where they are docked and preconditioned via the formation of a SNARE complex between vesicular proteins and plasma membrane proteins. Energy and control of these transports and reactions are provided by several kinds of enzymes and chaperone molecules. Arrival of an action potential causes depolarisation of the motoneurone axon terminal and opening of large conductance calcium channels. The last step, directly linked to calcium input, leads the membranes to fuse and acetylcholine to immediately leave the neuron towards the synaptic space.
Guiheneuc
P
P
Laboratoire de neurophysiologie clinique, CHU Nantes Hôtel-Dieu, 44035 Nantes cedex 01, France. pierre.guiheneuc@chu-nantes.fr
D000109:Acetylcholine / Q000493:pharmacokinetics* / Q000494:pharmacology*; D002118:Calcium / Q000493:pharmacokinetics; D002462:Cell Membrane / Q000502:physiology; D005089:Exocytosis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008565:Membrane Proteins / Q000502:physiology; D009469:Neuromuscular Junction / Q000502:physiology*; D050600:SNARE Proteins; D009435:Synaptic Transmission / Q000502:physiology*; D033921:Vesicular Transport Proteins
D008565:Membrane Proteins; D050600:SNARE Proteins; D033921:Vesicular Transport Proteins; D000109:Acetylcholine; D002118:Calcium