Serotonin loaded synaptic vesicles are docked, inside the synapse in the presynaptic cell, close to the plasmamembrane. The docking brings the vesicles in close proximity to the release site to fascilitate the release of serotonin. Some of the molecules involved in the docking process are Munc 18, Rab3a, Rab 3 interacting molecule (RIM). The priming reaction brings docked but unprimed synaptic vesicles into a releaseable pool. Priming involes formation of the trimeric SNARE complex between two plasmamembrane proteins SNAP25 and Syntaxin and vesicular membrane protein, VAMP2.