Chemical synaptic transmission serves as the main form of cell to cell comm
unication in the nervous system. Neurotransmitter release occurs through th
e process of regulated exocytosis, in which a synaptic vesicle releases its
contents in response to an increase in calcium. The use of genetic, bioche
mical, structural, and functional studies has led to the identification of
factors important in the synaptic vesicle life cycle. Here we focus on the
prominent role of SNARE (soluble NSF attachment protein receptor) proteins
during membrane fusion and the regulation of SNARE function by Rab3a, nSec1
, and NSE Many of the proteins important for transmitter release have homol
ogs involved in intracellular vesicle transport, and all forms of vesicle t
rafficking share common basic principles. Finally, modifications to the syn
aptic exocytosis pathway are very likely to underlie certain forms of synap
tic plasticity and therefore contribute to learning and memory.