FIGURE 1.

Clathrin-mediated endocytosis. Extracellular ligands binding to cell surface receptors triggers the recruitment of the adaptor proteins, such as AP-2, Dab2, and/or members of the epsin family, which induces plasma membrane invagination and formation of clathrin-coated pits that are subsequently released via dynamin-mediated scission. Clathrin-coated vesicles undergo de-coating and sorting through fusion with early endosomes, late endosomes, and ultimately, lysosomes, leading to receptor degradation, or sorting back to the cell surface by recycling endosomes.