Pathways and mechanisms of endocytic recycling

Studies of cargo proteins that are internalized independently of clathrin have revealed new pathways and mechanisms of endocytic recycling. Precise temporal and spatial regulation of recycling pathways is crucial for various cellular processes, including cytokinesis, cell adhesion, morphogenesis, cell fusion, learning and memory. Endocytic recycling is coordinated with endocytic uptake to control the composition of the plasma membrane. Although much of our understanding of endocytic recycling has come from studies on the transferrin receptor, a protein internalized through clathrin-dependent endocytosis, increased interest in clathrin-independent endocytosis has led to the discovery of new endocytic recycling systems. Recent insights into the regulatory mechanisms that control endocytic recycling have focused on recycling through tubular carriers and the return to the cell surface of cargoes that enter cells through clathrin-independent mechanisms. Recent work emphasizes the importance of regulated recycling in processes as diverse as cytokinesis, cell adhesion, morphogenesis, cell fusion, learning and memory.