Cell biology - A role for lipid shells in targeting proteins to caveolae, rafts, and other lipid domains

The surface membrane of cells is studded with morphologically distinct, regions, or domains, like microvilli, cell-cell junctions, and coated pits. Each of these domains is specialized for a particular function, such as nutrient absorption, cell-cell communication, and endocytosis. Lipid domains, which include caveolae and rafts, are one of, the least understood membrane domains. These domains are high in cholesterol and sphingolipids, have a light buoyant density, and function in both endocytosis and cell signaling. A major mystery, however, is how resident molecules are targeted to lipid domains. Here,we propose that the molecular address for proteins targeted to lipid, domains is a lipid shell.