Fig. 6. Common molecular machinery for transmitter release. (A) The proteolipid pore complex connects to the corresponding pore protein array in the plasma membrane; (B) calcium triggers a conformational change in the protein array and the ring structure opens; (C) the ring remains in a meta-stable open-confirmation, that is, it can widen and constrict rapidly (flickering); (D) eventually the pore closes; (E) the vesicle leaves the docking site; (F) the pore dilates, and the vesicle fuses with the plasma membrane (complete exocytosis); (G) the vesicle is retrieved by dynamin-clathrin-dependent endocytosis.
