BAR proteins are key components of the synaptic vesicle cycle in nerve terminals. They participate
in the regulation of neurotransmitter release during the fusion of synaptic vesicles with the presynaptic membrane and synaptic vesicle recycling. Localization of these proteins at the sites of liquid–liquid phase separation in nerve terminals suggests additional functions of these molecules. In the current review, we discuss the
tasks of BAR proteins at different stages of the secretory cycle, including their putative role in liquid–liquid
phase transitions in nerve terminals during synaptic activity. We suggest that BAR proteins, along with their
established functions in exo- and endocytosis, play crucial roles in the organization of the reserve pool of synaptic vesicles and at intermediate stages of the vesicle cycle.