Complexins regulate a late step in Ca2+-dependent neurotransmitter release
K Reim1, M Mansour, F Varoqueaux
1Max-Planck-Institut für Experimentelle Medizin, Abteilung Neurogenetik, AG Molekulare Neurobiologie, Hermann-Rein-Str. 3, D-37075 Göttingen, Bundesrepublik, Deutschland.
Abstract:
Synaptic vesicle fusion at synapses is triggered by increases in cytosolic Ca2+ levels. However, the identity of the Ca2+ sensor and the transduction mechanism of the Ca2+ trigger are unknown. We show that Complexins, stoichiometric components of the exocytotic core complex, are important regulators of transmitter release at a step immediately preceding vesicle fusion. Neurons lacking Complexins show a dramatically reduced transmitter release efficiency due to decreased Ca2+ sensitivity of the synaptic secretion process. Analyses of mutant neurons demonstrate that Complexins are acting at or following the Ca2+-triggering step of fast synchronous transmitter release by regulating the exocytotic Ca2+ sensor, its interaction with the core complex fusion machinery, or the efficiency of the fusion apparatus itself.
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