Clathrin-Independent Endocytosis - What We Know, What We Guess, What Is A Mystery

The history of clathrin-independent endocytosis has begun in the early nineties of the XX century. Despite the initial doubts as to whether this process exist at all, new techniques, that emerged in the late 1990s, confirmed the presence of new, clathrin-independent pathways. The best known among them are: caveolar, CLIC / GEEC, macropinocytosis and Arf6-dependent endocytosis. The internalization of ligands by these ways goes on at the specific domains of the cellular membrane, called lipid rafts. Lipid rafts, composed of cholesterol and phospholipids, are involved in the intracellular transport and signal transduction. The types of clathrin-independent endocytosis were defined by key proteins and lipids essential for different endocytic mechanisms, by the morphology of the resulting membrane structures, by the specificity of the load, and by the effects of inhibitors. Recently, new mechanisms of clathrin-independent endocytosis have emerged. Understanding of these processes and their regulatory systems can help to recognise the cell physiology and to design new therapeutic strategies.