Figure 8.

Model for the endocytic roles of actin, Hip1R and cortactin in endocytosis. (1) Hip1R binds to the clathrin coat, possibly stimulating or stabilizing its assembly on the inner face of the plasma membrane, and binds to actin filaments. (2) Dynamin assembles around the neck of the nascent CCV. Cortactin interacts with dynamin, stimulates the Arp2/3 complex to form branched actin filaments, and stabilizes the branched junctions. The actin meshwork grows via new filament assembly at the vesicle neck. The actin network is anchored to the clathrin coat by Hip1R, so that the vesicle is pushed away from the plasma membrane. Hip1R forms a complex with cortactin to cap actin filament barbed ends near the clathrin coat.