May play a role in regulated exocytosis. May indirectly regulate the activity of the plasma membrane dopamine transporter SLC6A3 and thereby regulate dopamine transport back from the synaptic cleft into the presynaptic terminal. Interacts (via N-terminus) with SLC6A3 (via N-terminus). May interact with VMAT2. Found at the neuromuscular synapses. Belongs to the synaptogyrin family.