Presynaptic calcium and control of vesicle fusion

Curr Opin Neurobiol. 2005 Jun;15(3):266-74. doi: 10.1016/j.conb.2005.05.006.


Vesicle fusion and transmitter release at synapses is driven by a highly localized Ca2+ signal that rapidly builds up around open Ca2+-channels at and near presynaptic active zones. It has been difficult to estimate the amplitude and the kinetics of this 'microdomain' signal by direct Ca2+-imaging approaches. Recently, Ca2+ uncaging at large CNS synapses, among them the calyx of Held, has shown that the intrinsic cooperativity of Ca2+ in inducing vesicle fusion is high, with 4-5 Ca2+ ions needed to trigger vesicle fusion. Given the Ca2+-sensitivity of vesicle fusion as determined by Ca2+-uncaging, it was found that a surprisingly small (10-25 microM) and brief (<1 ms) local Ca2+ signal is sufficient to achieve the amount, and the kinetics of the physiological transmitter release. The high cooperativity of Ca2+ in inducing vesicle fusion and the non-saturation of the Ca2+-sensor for vesicle fusion renders small changes of the local Ca2+-signal highly effective in changing the release probability; an insight that is important for our understanding of short-term modulation of synaptic strength.

Publication types

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

MeSH terms

  • Calcium / metabolism*
  • Central Nervous System / metabolism
  • Models, Neurological*
  • Neurotransmitter Agents / metabolism
  • Presynaptic Terminals / metabolism*
  • Synaptic Vesicles / metabolism*


  • Neurotransmitter Agents
  • Calcium