cofactor:Binds 3 calcium ions per subunit. The ions are bound to the C2 domains.,domain:The first C2 domain mediates Ca(2+)-dependent phospholipid binding.,function:May be involved in Ca(2+)-dependent exocytosis of secretory vesicles through Ca(2+) and phospholipid binding to the C2 domain or may serve as Ca(2+) sensors in the process of vesicular trafficking and exocytosis.,similarity:Belongs to the synaptotagmin family.,similarity:Contains 2 C2 domains.,subunit:Homodimer. Can also form heterodimers.,