The molecular machinery for secretion is conserved from yeast to neurons.

A variety of approaches have been utilized to identify and characterize the molecules that mediate vesicular trafficking along the secretory pathway. Two approaches that have been particularly fruitful include the genetic dissection of the yeast secretory pathway and the biochemical characterization of proteins involved in the synaptic vesicle membrane trafficking in the mammalian nerve terminal. The recent convergence of these approaches suggests that common mechanisms may underlie a wide variety of vesicle-mediated transport steps. We discuss the results that support this possibility and propose a model for synaptic vesicle docking and fusion that incorporates evolutionarily conserved elements that may be part of a constitutive fusion machinery and specialized elements that may mediate regulatory events that are specific to the process of neurotransmitter release.