Protein Targeting - Receptor-mediated Endocytosis

Receptor-mediated Endocytosis

Several molecules that attach to special receptors called clathrin coated pits on the outside of cells cause the cell to perform endocytosis, an invagination of the plasma membrane to incorporate the molecule and associated structures into endosomes. This mechanism is used for three main purposes:

• Uptake of essential metabolites, for example, LDL.
• Uptake of some hormones and growth factors, for example, epidermal growth factor and nerve growth factor.
• Uptake of proteins that are to be destroyed, for example, antigens in phagocytotic cells like macrophages.

Receptor-mediated endocytosis can also be "abused":

• Some viruses, for example, the Semliki forest virus, enter the cell through this mechanism.
• Cholera, diphtheria, anthrax, tetanus, botulinum, and other bacterial toxins enter the cell this way.