Neurotransmitter release is triggered by a calcium-induced rearrangement in the Synaptotagmin-1/SNARE complex primary interface.

triggering, synaptotagmin-1 continues to contact the SNAREs at one site but disconnects the other site. We propose that this switch generates a pulling force on the SNARE complex that in turn triggers release. Biochemical and modeling studies described in the accompanying paper support this hypothesis.