ClathrinBindung

ClathrinBinding is the interaction between clathrin and adaptor or accessory proteins that drive the assembly of clathrin-coated vesicles in classical clathrin-mediated trafficking. It is essential for endocytosis at the plasma membrane and for sorting in the trans-Golgi network and endosomes. In clathrin-mediated endocytosis, cargo receptors recruit adaptor protein complexes such as AP-2 to specific membrane sites. Adapters recognize sorting motifs on cargo proteins and simultaneously engage clathrin via clathrin-binding motifs present in many adaptor and accessory proteins. The clathrin triskelion, formed by three clathrin heavy chains and light chains, polymerizes into a polyhedral lattice on the cytosolic surface of the membrane, converting the membrane into a coated pit that invaginates to form a vesicle.

Accessory proteins such as epsin, amphiphysin, and dynamin contribute to membrane curvature, cargo selection, and scission. The interaction between clathrin and adaptors is regulated by phosphoinositides, particularly PIP2, and by the conformational state of AP-2, which switches from a closed to an open form to expose clathrin-binding sites. Uncoating of vesicles after budding is driven by Hsc70 and auxilin.

Disruption of clathrin binding or its regulation can impair endocytosis, trafficking to lysosomes, and receptor turnover, with implications for cellular signaling and disease. Clathrin binding is thus a central step in vesicular transport and intracellular sorting.