BAR Domain Proteins as Putative Regulators of the Protein Liquid Phase in Nerve Terminals in the Central Nervous System

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.