Key Events in Synaptic Vesicle Endocytosis

A synaptic release site is characterized by a pool of synaptic vesicles aggregated to an active zone at the presynaptic plasma membrane. When an action potential arrives, calcium channels in the active zone open to generate a steep increase in calcium concentration. Calcium binds the synaptic vesicle protein synaptotagmin which promotes its interaction with the SNARE complex and with the plasma membrane, together triggering fusion of the synaptic vesicle membrane with the plasma membrane (1). Following fusion, the synaptic vesicle membrane needs to be removed from the plasma membrane to prevent its expansion, and recycling of the vesicle components is needed to refill the pool of vesicles at the release site.