Synaptotagmins(Syts) are a large gene family of synaptic vesicle integral membrane proteins. Syt functions as regulators of both exocytosis /endocytosis and is involved in neurotransmitter secretion from small secretory vesicles. 13 isoforms of Syt have been identified(SytI-XIII). SynaptotagminVI is localized to the endoplasmic reticulum and/or Golgi-like perinuclear compartment. It may be important for trafficking and calcium signaling as it is specially expressed in nonneuronal tissues. Also SytVI is present in the acrosomal region of mammalian spermatozoa. The cytosolic domain of SytVI can abrogate exocytosis by competing with the endogenous protein for essential interactions with the fusion machinery involved in a acrosomal exocytosis.