Complexin: Does It Deserve Its Name?

Knockout and other perturbations of complexins have provided important insights and elicited controversies about their role in neurotransmitter release. New work by Yang et al. in this issue of Neuron adds important detail and complexity to existing concepts-particularly on the nature of a Ca2+-dependent complexin-synaptotagmin switch for the triggering of exocytosis. But it also provokes thoughts about alternative interpretations, which might result in a simpler model of complexin function.