clathrin coat

Definition

Target type: cellularcomponent

A membrane coat found on coated pits and some coated vesicles; consists of polymerized clathrin triskelions, each comprising three clathrin heavy chains and three clathrin light chains, linked to the membrane via one of the AP adaptor complexes. [GOC:mah, PMID:11252894, PMID:9531549]

The clathrin coat is a protein complex that plays a crucial role in endocytosis, the process by which cells internalize molecules and particles from their surroundings. It is a specialized protein assembly that forms a cage-like structure around invaginating regions of the plasma membrane, capturing specific cargo molecules and facilitating their internalization into the cell. The clathrin coat is composed of three major protein components: clathrin, adaptor proteins (APs), and accessory proteins.

Clathrin is a triskelion-shaped protein that forms a lattice-like structure, resembling a basket woven from three-legged structures. These triskelions assemble into polygonal cages, typically with a pentagonal or hexagonal shape. Each triskelion consists of three heavy chains and three light chains, connected at their base by a hub. The clathrin coat provides the structural framework for the budding vesicle.

Adaptor proteins (APs) act as the bridge between the clathrin coat and the cargo molecules. They bind to specific signal sequences on cargo proteins and interact with clathrin, thereby recruiting cargo into the budding vesicle. There are four major types of AP complexes: AP-1, AP-2, AP-3, and AP-4, each with distinct roles in different cellular processes. AP-2 is the primary adaptor protein complex involved in clathrin-mediated endocytosis at the plasma membrane. AP-1, AP-3, and AP-4 are primarily involved in intracellular trafficking between different compartments, such as the Golgi and endosomes.

Accessory proteins play a variety of roles in regulating clathrin-mediated endocytosis. These proteins include dynamin, which is required for the pinching off of the clathrin-coated vesicle from the plasma membrane; auxilin, which promotes the uncoating of clathrin from the vesicle; and other proteins that regulate the assembly and disassembly of the clathrin coat.

The clathrin coat is highly dynamic and constantly forming and disassembling as cells internalize cargo. This dynamic process is tightly regulated by a complex interplay of various proteins and signaling pathways. The clathrin coat is essential for a wide range of cellular functions, including nutrient uptake, receptor signaling, and the regulation of cell surface receptors. Defects in clathrin-mediated endocytosis can lead to various diseases, highlighting the importance of this crucial cellular process.'
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Proteins (1)

Compounds (6)