Clathrinavhengige

Clathrinavhengige, or clathrin-dependent endocytosis, is a major cellular pathway for internalizing extracellular ligands, receptors, and other membrane-associated molecules. It relies on the coat protein clathrin to sculpt plasma membrane regions into vesicles, allowing selective cargo uptake and trafficking within the cell.

The process begins with cargo selection, often mediated by adaptor protein complexes such as AP-2, which recognize sorting signals in the cytoplasmic tails of transmembrane proteins and recruit clathrin to the plasma membrane. This leads to the formation of a clathrin-coated pit that progressively grows as additional adaptor and accessory proteins assemble. The curvature and stabilization of the membrane are facilitated by clathrin triskelions and BAR-domain-containing proteins, among others.

Once the pit matures, dynamin molecules assemble at the neck of the forming vesicle and hydrolyze GTP to sever the vesicle from the plasma membrane. The released clathrin-coated vesicle then undergoes uncoating, a reaction driven by auxilin and the chaperone Hsc70, which frees the vesicle to fuse with early endosomes.

Recycling and trafficking follow: receptors and cargo are sorted in endosomes, with many receptors returning to the plasma membrane via recycling pathways. The process is tightly regulated by phosphoinositides, kinases, and interacting proteins, and is essential for nutrient uptake, receptor signaling modulation, and protein homeostasis. Examples of cargo include the transferrin receptor, low-density lipoprotein receptor, and several growth factor receptors. Clathrin-dependent endocytosis is distinct from clathrin-independent pathways, such as caveolin-mediated endocytosis or macropinocytosis.