clathrin coat of coated pit

Definition

Target type: cellularcomponent

The coat found on coated pits and the coated vesicles derived from coated pits; comprises clathrin and the AP-2 adaptor complex. [GOC:mah]

The clathrin coat of a coated pit is a complex structure composed of several proteins that play a crucial role in endocytosis, the process by which cells internalize molecules and particles from their surroundings. Here's a detailed description of its cellular components:

**Clathrin:** The core component of the coat, clathrin is a triskelion-shaped protein composed of three heavy chains and three light chains. These triskelions assemble into a lattice-like structure that forms the characteristic polygonal cage of the coated pit.

**Adaptor Proteins (APs):** These proteins act as adaptors between the clathrin coat and the cargo molecules destined for internalization. There are four major types of AP complexes (AP-1, AP-2, AP-3, and AP-4), each with specific roles in sorting and trafficking different cargo molecules. AP-2 is the primary adaptor protein involved in clathrin-mediated endocytosis at the plasma membrane.

**Other Associated Proteins:** In addition to clathrin and APs, a number of other proteins are associated with the clathrin coat, including:

* **Dynamin:** This GTPase protein is crucial for the pinching off of the coated vesicle from the plasma membrane. It assembles as a ring around the neck of the budding vesicle and uses the energy from GTP hydrolysis to constrict the neck and release the vesicle.
* **Auxilin and Hsc70:** These proteins work together to disassemble the clathrin coat after vesicle formation, recycling clathrin and APs for further rounds of endocytosis.
* **Cargo Receptors:** These transmembrane proteins bind specific cargo molecules within the cell and are recruited to the clathrin-coated pit.

**Functional Importance:** The clathrin coat plays a critical role in mediating selective uptake of various molecules, including nutrients, hormones, growth factors, and signaling molecules. It also serves as a mechanism for the internalization of viruses and bacteria. By controlling the composition of the clathrin coat, cells can ensure that the correct cargo molecules are internalized, ensuring efficient and precise regulation of cellular processes.'
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Proteins (1)

Compounds (7)