Module 4: Figure vesicle cycle
The exocytotic vesicle cycle.
1. Docking. A vesicle held within the reserve pool of vesicles embedded in a cytoskeletal matrix moves towards the membrane and uses its vesicle soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptors (v-SNAREs) to dock with the target SNAREs (t-SNAREs) in the plasma membrane. 2. Priming. The vesicle is primed through an ATP-dependent process that prepares the exocytotic machinery for fusion. 3. Fusion. Upon membrane depolarization, Ca2+ entering through a voltage-operated channel (VOC) triggers membrane fusion: the process of exocytosis (Module 4: Figure Ca2+-induced membrane fusion). 4. Endocytosis. The membrane of the empty vesicle is retrieved through a process of endocytosis.