In a neuron, synaptic vesicles (or neurotransmitter vesicles) store various neurotransmitters that are released at the synapse. The release is regulated by a voltage-dependent calcium channel. Vesicles are essential for propagating nerve impulses between neurons and are constantly recreated by the cell. The area in the axon that holds groups of vesicles is an axon terminal or "bouton". Up to 130 vesicles can be released per bouton over a ten-minute period of stimulation at 0.2 Hz. In the human brain region V1 synaptic vesicles have an average diameter of 39.5 nanometers with a standard deviation of 5.1 nanometers.

Synaptic vesicles are relatively simple because only a limited number of proteins fit into a sphere of 40 nm diameter. Purified vesicles have a protein:phospholipid ratio of 1:3 with a lipid composition of 40% phosphatidylcholine, 32% phosphatidylethanolamine, 12% phosphatidylserine, 5% phosphatidylinositol, and 10% cholesterol.

Synaptic vesicles contain two classes of obligatory components: transport proteins involved in neurotransmitter uptake, and trafficking proteins that participate in synaptic vesicle exocytosis, endocytosis, and recycling.

Randy W. Schekman (born December 30, 1948) is an American cell biologist at the University of California, Berkeley and former Editor-in-Chief of Proceedings of the National Academy of Sciences. In 2011 he was announced as the editor of eLife a new high profile open access journal published by the Howard Hughes Medical Institute, the Max Planck Society and the Wellcome Trust launching in 2012. He was elected to the National Academy of Sciences in 1992.

In 2002, Schekman received the Albert Lasker Award for Basic Medical Research and Louisa Gross Horwitz Prize of Columbia University along with James Rothman for their discovery of cellular membrane trafficking, a process that cells use to organize their activities and communicate with their environment.

The Schekman laboratory carries out research into molecular descriptions of the process of membrane assembly and vesicular traffic in eukaryotic cells including yeast.