May have a regulatory role in the membrane interactions during trafficking of synaptic vesicles at the active zone of the synapse. It binds acidic phospholipids with a specificity that requires the presence of both an acidic head group and a diacyl backbone. Binds 3 Ca(2+) ions per subunit. The ions are bound to the C2 domains. Homodimer or homotrimer (possible). Synaptic vesicles in neurons. Belongs to the synaptotagmin family.