Synaptotagmin-1 is a synaptic vesicle membrane glycoprotein that is widely expressed throughout the CNS and is generally thought to act as the Ca2+ sensor in the regulation of exocytosis and neurotransmitter release (Littleton and Bellen 1995). Recent studies indicate that Synaptotagmin's Ca2+ mediated binding of SNAP25 is essential for the Ca2+ dependent triggering of membrane fusion (Zhang et al., 2002). It has recently been demonstrated that discrete residues within the c(2)b binding domain of synaptotagmin 1 independently specify endocytic rate and synaptic vesicle size (Poskanzer et al., 2006).Synonyms: SVP65, SYT, SYT1, Synaptotagmin I, Synaptotagmin1, SytI, p65