A unifying hypothesis for acetylcholine release

Mediatophore is the only nerve terminal membrane protein known to translocate acetylcholine upon calcium action. It is localized at the active zone. In this review we attempted to describe its role in relation to the vesicular and membrane protein complexes that are formed at the active zone. The model pictures a possible set of sequential steps that lead to exocytosis. The smallest quantal events are attributed to mediatophore opening momentarily, while synaptic vesicles synchronize release by controlling the calcium microdomain. A clear distinction is made between sub-quantal ACh release preserved after Botulinum toxin action, and exocytosis of vesicular contents. A cybernetic model for release and exocytosis related to protein interactions is presented for future works.