ENDOCYTOSIS
Endocytosis is a process by which a small region of the plasma membrane of a cell ivaginates to form a new intracellular vesicle. The plasma membrane ivagination is termed caveolae and the caveolin is a protein which lines the caveolae.
The central role of endocytosis is well exhibited in receptor regulation, neurotransmitters and the delivery of drugs and also endocytosis can be in other forms which are pinnocytosis and phagocytosis (Liang et al., 2010). With respect to receptor-mediated endocytosis, a specific receptor on the cell surface binds to the extracellular molecule (Ligand). The area which contains the receptor- ligand complex goes through endocytosis by becoming a vesicle. Among common ligands which most vertebrates
…show more content…
The movement of the endocytosed protein which is destined for the apical surface to fuse with and also the movement of extracellular materials from one side of the epithelial cells to another can be termed as transcytosis. With respect to concept, transcytosis can be grouped into three processes namely; endocytosis, exocytosis and transcellular transport (Pravda,2011). Though transcytosis is tightly controlled by the cell it also has the potential for transepithelial movement of bacteria and other pathogens, hence it sometimes becomes an etiologic factor in the body(Pravda,2011). Trancytosis occurs in hepatocytes and this phenomenon is a typical example of transcellular transport . Here the apical membrane form bile and the basolateral membrane face blood. All newly synthesized apical and basolateral proteins are sent to the golgi to the basolateral membrane. From here both proteins are endocytosed in the same vesicle,but take different pathways.They both are also sorted into transport vesicles where some move to the basolateral and others move to fuse with the apical membrane. An importance of transcytosis is that through endothelial cells, drugs can pass through the BBB into the brain and also avoid efflux by ABC transporters(Georgieva,Hoekstra and Zuhorn,