Exocytosis
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Exocytosis is a form of active transport in which a cell transports molecules out of the cell. As an active transport mechanism, exocytosis requires the use of energy to transport material. Exocytosis
Molecular machinery driving exocytosis in neuromediator release. The core SNARE complex is formed by four α-helices contributed by synaptobrevin, syntaxin and SNAP-25, synaptotagmin serves as a calcium sensor and regulates intimately the SNARE zipping.
In the lipid-lined pore theory, both membranes curve toward each other to form the early fusion pore. When the two membranes are brought to a "critical" distance, the lipid head-groups from one membrane insert into the other, creating the basis for the fusion pore.
Endocytosis
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Endocytosis is a cellular process in which substances are brought into the cell. The material to be internalized is surrounded by an area of cell membrane, which then buds off inside the cell to form
Exocytosis
…proteins) out of the cell. As an active transport mechanism, exocytosis requires the use of energy to transport material. Exocytosis and its counterpart, endocytosis, are used by all cells because most chemical substances important to them are large polar molecules that cannot pass through the hydrophobic portion…
Schematic drawing illustrating clathrin-mediated (left) and clathrin-independent endocytosis (right) of synaptic vesicle membranes
From left to right: Phagocytosis, Pinocytosis, Receptor-mediated endocytosis.
Stage 1
Stage 2