Involved in exocytosis by regulating a late step in synaptic vesicle fusion. Could play a role in neurotransmitter release by regulating membrane flow in the nerve terminal (By similarity). Plays a role in the recruitment of endophilin unc-57 to synaptic vesicles (PubMed:21029864). Probably by controlling dense-core vesicle trafficking, plays a role in the AVG neuron-mediated formation of the right axon tract of the ventral nerve cord (PubMed:27116976). Belongs to the small GTPase superfamily. Rab family.