Cell trafficking encompasses the wide variety of processes that go into the movement of cargo (typically proteins, pathogens and other macromolecules) using membrane bound transport vesicles. This transport can take place within different organelles in the same cell, or across the cell membrane to and from the extracellular environment. Much like a parcel sorting office, the cell uses a complex, highly regulated system to make sure that the right cargo is delivered to the correct location Both endocytosis and exocytosis utilize small compartments of membrane to enclose their cargo. These transport vesicles bud off from one membrane and can dynamically fuse with other membranes, or split up into smaller vesicles by fission. Residing within the interior, or lumen, of the transport vesicles, the cargo is protected from the cytoplasm. As the lumen of transport vesicles is physiologically similar to other membrane bound organelles and the extracellular space, transfer of cargo does not require movement across a membrane, simply fusion between vesicles.ransport vesicles differ from one another in the type of cargo they ferry from one site to another, the route they take, and the presence or absence of proteins on the cytosolic surface, which can form a coat. These coat proteins self-assemble on the membrane, helping to collect and concentrate the vesicle cargo. There are three well-characterised coat proteins, which coat vesicles at various points during endocytosis and exocytosis. Clathrin-coated vesicles mediate endocytosis from the plasma membrane to endosomal compartments and the Golgi. The next steps in endocytosis, namely retrograde transport within the Golgi and towards the ER Once the coated vesicle bud grows and is ready to detach, it has to be separated from the membrane of origin without loss of cargo. In some cases, the detachment of budded vesicles from the plasma membrane may be facilitated by the GTPase Dynamin, via membrane scission. Dynamins associate at the neck of the budding vesicle, and fuse the two lipid bilayers together in a GTP-dependent process, thereby cutting the neck and releasing the vesicle from the membrane. In order to bend the membrane to promote or discourage scission, BAR, N-BAR and F-BAR domain proteins affect membrane curvature, either promoting or discouraging the likelihood of membrane scission