N-terminal domain of synaptotagmin-1 and -2
The synaptotagmins are integral membrane proteins of synaptic vesicles thought to serve as Ca(2+) sensors in the process of vesicular trafficking and exocytosis. Calcium binding to synaptotagmin-1 participates in triggering neurotransmitter release at the synapse. In general, synaptotagmins contain 2 calcium binding C2 domains. Synaptotagmin-1 and -2 have an additional N-terminal domain that has been shown to bind to Botulinum neurotoxin B.
Jiyao W et al.(2023). "The conserved domain database in 2023.",