Heuser–Reese cycle endocytosis

The below exocytosis, synaptic vesicles are recycled within 30–60 s by using the endocytosis. At first, vesicle membrane obtains a clathrin coat; distorting it therefore it invaginates into the terminal. Next a (GTP)-guanosine triphosphate-binding protein, dynamin, forms a collar around the neck of the invagination. The Hydrolysis of bound GTP triggers the fission of the coated vesicle from the presynaptic membrane. The GTP-bound form of dynamin needs calcium, therefore the similar rise in nerve terminal Ca²⁺ concentration is responsible for exocytosis and it also enables endocytosis. Once it is free in the terminal the vesicle loses its clathrin coat which is as shown in figure below:

                                                                   Figure: The Vesicle endocytosis.