Regulating the clathrin-coated vesicle cycle by AP2 subunit phosphorylation

Clathrin-coated pits form from the concerted assembly of many different protein components that interact with each other and with the lipid bilayer. When the coated pit pinches off to form a coated vesicle, the coat is removed to allow fusion of the endocytic vesicle with an early endosome, and the disassembled coat components can then recycle through the cytosol to participate in new rounds of coated pit formation. One potential mechanism to regulate the cycles of coat protein assembly and disassembly is reversible phosphorylation, particularly given that many of the coat components, such as the AP2 adaptor complex, are phosphorylated on multiple sites both in vitro and in vivo. Recent studies have provided particular insight into the role of phosphorylation of the cargo-binding micro2 subunit of AP2.