AP-2 adaptor complex

Definition

Target type: cellularcomponent

A heterotetrameric AP-type membrane coat adaptor complex that consists of alpha, beta2, mu2 and sigma2 subunits, and links clathrin to the membrane surface of a vesicle, and the cargo receptors during receptor/clathrin mediated endocytosis. Vesicles with AP-2-containing coats are normally found primarily near the plasma membrane, on endocytic vesicles. In at least humans, the AP-2 complex can be heterogeneric due to the existence of multiple subunit isoforms encoded by different alpha genes (alphaA and alphaC). [GOC:mah, PMID:10611976, PMID:21097499, PMID:22022230, PMID:24322426]

The AP-2 adaptor complex is a protein complex involved in clathrin-mediated endocytosis, a process that brings molecules from the plasma membrane into the cell. It is a heterotetrameric complex composed of two large subunits, α-adaptin and β2-adaptin, a medium subunit, μ2, and a small subunit, σ2. The complex has a characteristic structure with a "trunk" domain that binds to clathrin and a "ear" domain that interacts with cargo molecules.

The α-adaptin subunit is responsible for binding to clathrin and for interacting with the plasma membrane. It has a clathrin-binding domain and a phosphoinositide-binding domain that allows it to bind to the membrane. The β2-adaptin subunit is responsible for binding to cargo molecules and for interacting with the μ2 subunit. It has a "trunk" domain that interacts with the μ2 subunit and an "ear" domain that binds to cargo molecules.

The μ2 subunit acts as a bridge between the α-adaptin and β2-adaptin subunits. It has a tyrosine-based sorting signal that allows it to interact with cargo molecules. The σ2 subunit is a small, regulatory subunit that plays a role in the assembly and disassembly of the AP-2 complex.

The cellular component of the AP-2 complex can be localized to the plasma membrane, where it participates in the formation of clathrin-coated pits, or in the cytoplasm, where it is involved in the assembly and disassembly of the complex. The specific location of the AP-2 complex within the cell is influenced by various factors, including the presence of cargo molecules and the phosphorylation state of the complex.

The AP-2 complex is essential for the proper functioning of many cellular processes, including signal transduction, cell migration, and nutrient uptake. Dysregulation of AP-2 complex function has been implicated in several human diseases, such as cancer and neurodegenerative disorders. In summary, the AP-2 adaptor complex plays a crucial role in clathrin-mediated endocytosis, a fundamental cellular process responsible for the internalization of various molecules from the plasma membrane.'
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Proteins (1)

Compounds (5)