synaptotagmin7

Synaptotagmin-7 (Syt-7, SYT7) is a member of the synaptotagmin family, a group of membrane-trafficking proteins that act as calcium sensors to trigger membrane fusion events. Like other synaptotagmins, Syt-7 contains two cytoplasmic C2 domains (C2A and C2B) that bind calcium and phospholipids, and a single transmembrane helix that anchors the protein to membranes. This structural arrangement supports its role in regulating vesicle fusion events in response to calcium signals.

Expression of SYT7 is broad, with notable presence in neurons as well as non-neuronal cells. In neurons, Syt-7 is found on synaptic vesicles and other membrane compartments, including lysosome-related organelles, where it participates in calcium-driven exocytic processes. Its distribution supports diverse functions across cell types, extending beyond classic neurotransmitter release.

In the nervous system, Syt-7 is thought to function as a high-affinity calcium sensor for asynchronous neurotransmitter release. It contributes to slower, ongoing vesicle fusion that follows the rapid, synchronous release mediated by other synaptotagmins, and may also help regulate vesicle replenishment and short-term synaptic plasticity under certain activity conditions.

Beyond neurotransmission, Syt-7 is implicated in calcium-dependent lysosomal exocytosis and membrane repair. In non-neuronal cells, it can trigger fusion of lysosomes with the plasma membrane, a process important for secretion and cellular remodeling. Through its interactions with SNARE proteins and lipids, Syt-7 helps coordinate vesicle fusion and endo- and exocytic trafficking across diverse cellular contexts.

Overall, synaptotagmin-7 is a calcium-sensitive regulator of vesicle fusion with roles in both neuronal communication and lysosome-mediated secretion pathways.