CLATHRIN-COATED VESICLE FORMATION AND PROTEIN SORTING - AN INTEGRATEDPROCESS

Clathrin-coated vesicles were the first discovered and remain the most extensively characterized transport vesicles. They mediate endocytosi s of transmembrane receptors and transport of newly synthesized lysoso mal hydrolases from the trans-Golgi network to the lysosome. Cell-free assays for coat assembly, membrane binding, and coated vesicle buddin g have provided detailed functional and structural information about h ow the major coat constituents, clathrin and the adaptor protein compl exes, interact with each other, with membranes, and with the sorting s ignals found on cargo molecules. Coat constituents not only serve to s hape the budding vesicle, but also play a direct role in the packaging of cargo, suggesting that protein sorting and vesicle budding are fun ctionally integrated. The functional interplay between the coated vesi cle machinery and its cargo could ensure sorting fidelity and packagin g efficiency and might enable modulation of vesicular trafficking in r esponse to demand.