receptor-mediated endocytosis

Definition

Target type: biologicalprocess

An endocytosis process in which cell surface receptors ensure specificity of transport. A specific receptor on the cell surface binds tightly to the extracellular macromolecule (the ligand) that it recognizes; the plasma-membrane region containing the receptor-ligand complex then undergoes endocytosis, forming a transport vesicle containing the receptor-ligand complex and excluding most other plasma-membrane proteins. Receptor-mediated endocytosis generally occurs via clathrin-coated pits and vesicles. [GOC:mah, ISBN:0716731363]

Receptor-mediated endocytosis is a highly specific cellular process that involves the uptake of molecules from the extracellular environment into the cell through the invagination and internalization of the plasma membrane. This process is mediated by specialized transmembrane proteins called receptors, which bind to specific ligands, such as hormones, growth factors, nutrients, and even viruses.

The process begins with the binding of the ligand to its specific receptor on the cell surface. This interaction triggers a series of events leading to the formation of a coated pit, a small indentation in the plasma membrane. These pits are typically coated with a protein complex known as clathrin, which plays a crucial role in the budding and internalization of the vesicle.

As the ligand-receptor complex accumulates in the coated pit, the clathrin coat begins to assemble, forming a cage-like structure around the pit. This structure helps to deform the membrane and facilitate the pinching off of the coated pit from the plasma membrane. This process results in the formation of a small, spherical vesicle called an endosome, which is enclosed by the clathrin-coated membrane.

Once the endosome is formed, it detaches from the plasma membrane and moves into the cytoplasm. The clathrin coat then disassembles, allowing the endosome to fuse with other intracellular compartments, such as early endosomes and lysosomes. Within these compartments, the ligand is either sorted for degradation or recycled back to the plasma membrane.

Receptor-mediated endocytosis is a highly regulated process that ensures the efficient uptake of specific molecules into the cell. It plays a critical role in a wide range of cellular processes, including:

* **Signal transduction:** Many hormones and growth factors exert their effects through receptor-mediated endocytosis. Upon internalization, the ligand-receptor complex can activate intracellular signaling pathways, leading to a variety of cellular responses.
* **Nutrient uptake:** Cells utilize receptor-mediated endocytosis to import essential nutrients, such as iron and cholesterol, from the extracellular environment.
* **Immune defense:** Receptor-mediated endocytosis is essential for the internalization and processing of antigens by immune cells, leading to the activation of the adaptive immune response.
* **Viral entry:** Some viruses exploit receptor-mediated endocytosis to enter cells. They bind to specific receptors on the cell surface, triggering their internalization and subsequent infection.

In summary, receptor-mediated endocytosis is a sophisticated cellular process that involves the specific uptake of molecules through the invagination and internalization of the plasma membrane. This process is essential for a variety of cellular functions and plays a crucial role in maintaining cellular homeostasis and responding to environmental stimuli.'
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Proteins (16)

Compounds (491)