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Endocytosis is triggered when a specific receptor is activated in receptor-mediated endocytosis. The function of receptor-mediated endocytosis is diverse. It is widely used for the specific uptake of certain substances required by the cell (examples include LDL via the LDL receptor or iron via transferrin ).
Uptake of extracellular molecules is also believed to be specifically mediated via receptors in caveolae. From left to right: Phagocytosis, Pinocytosis, Receptor-mediated endocytosis. Potocytosis is a form of receptor-mediated endocytosis that uses caveolae vesicles to bring molecules of various sizes into the cell. Unlike most endocytosis that ...
Ionotropic receptors allow for ions to pass through when agonized by a ligand. The main model involves a receptor composed of multiple subunits that allow for coordination of ion preference. G protein coupled receptors, also called metabotropic receptors, when bound to by a ligand undergo conformational changes yielding in intracellular response.
An antagonist is a chemical that acts within the body to reduce the physiological activity of another chemical substance (such as an opiate); especially one that opposes the action on the nervous system of a drug or a substance occurring naturally in the body by combining with and blocking its nervous receptor.
Receptor-mediated endocytosis is a form of pinocytosis where a cell takes in specific molecules or solutes. Proteins with receptor sites are located on the plasma membrane, binding to specific solutes. The receptor proteins that are attached to the specific solutes go inside coated pits, forming a vesicle.
When insulin binds to its receptors on the surface of a cell, the hormone receptor complex undergoes endocytosis and is subsequently attacked by intracellular lysosomal enzymes. [3] The internalization of the insulin molecules provides a pathway for degradation of the hormone, as well as for regulation of the number of sites that are available ...
Like other types of receptor-mediated endocytosis, potocytosis typically begins when an extracellular ligand binds to a receptor protein on the surface of a cell, thus beginning the formation of an endocytotic vesicle. The ligand is usually of low molecular mass (e.g. vitamins), but some larger molecules (such as lipids) can also act as ligands.
Molecules that follow these pathways include the receptors for LDL, epidermal growth factor (EGF), and the iron transport protein transferrin. Internalization of these receptors from the plasma membrane occurs by receptor-mediated endocytosis. LDL is released in endosomes because of the lower pH, and the receptor is recycled to the cell surface.