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 (By similarity). Involved in necrotic cell death (PubMed:22157748). Binds 3 Ca(2+) ions per subunit. The ions are bound to the C2 domains. And vesicle-like structures. Localized to regions known to be rich in synapses and appears to be associated with synaptic vesicles. Also found in some non-neuronal secretory structures. Worms exhibit severe behavioral abnormalities that are characteristic of deficiencies in synaptic function, including severe locomotion, feeding, and defecation defects (PubMed:8391930). Increased survival in response to hypoxia induced by sodium azide (PubMed:22157748). Reduces the formation of neuron cell corpses in a hyperactive mec-4 or deg-3 mutant background (PubMed:22157748). Belongs to the synaptotagmin family.