Synaptotagmins are a family of at least 15 Ca2+-binding, membrane-trafficking proteins that act as calcium sensors regulating neurotransmitter release. Synaptotagamins are expressed in both vesicular and plasma membranes where they are involved in lipid rearrangements required during synaptic vesicle fusion. Synaptotagmins also interact with calcium channels, sodium channels, ß-SNAP, neurexins, and other neural proteins in the absence of Ca2+, suggesting a role in presynaptic functions. Synaptotagmins exhibit differential expression, with synaptotagmins 1-5 expressed primarily in neural and endocrine tissues. Northern blots in murine brain tissue suggest synaptotagmin 1 is primarily expressed in rostral brain regions but has low expression in regions related to motor functions.Synonyms: SYT-2, SYT2, SYTII, Synaptotagmin 2, Synaptotagmin II