Clathrin-dependent or not: is it still the question?
Whether the endocytic uptake of a given molecule is mediated through clathrin-coated pits or not is a classical criterion used to characterize its endocytic pathway(s). Hence, clathrin-dependent endocytosis has been associated with highly selective and efficient uptake, whereas clathrin-independent endocytosis appeared to be confined to bulk uptake of fluid-phase markers. This scholastic view has recently been challenged using newly developed molecular tools that allow for the first time a functional and mechanistic analysis of these less well-characterized clathrin-independent pathways, including caveolar uptake and macropinocytosis. Furthermore, several studies point to a critical role of lateral lipid asymmetry--lipid rafts/microdomains--in membrane sorting. We will discuss the potential role of these structures in endocytosis and the possibility that differential sorting at the plasma membrane predisposes the ensuing intracellular fate of a given molecule as well as its physiological function.
Johannes
Ludger
L
Institut Curie, UMR144 CNRS, Traffic and Signaling Laboratory, 26 rue d'Ulm, 75005 Paris Cedex 05, France. ludger.johannes@curie.fr
Lamaze
Christophe
C
D000818:Animals; D021941:Caveolae / Q000378:metabolism; D002966:Clathrin / Q000502:physiology*; D022163:Clathrin-Coated Vesicles / Q000502:physiology; D003034:Coated Pits, Cell-Membrane / Q000502:physiology; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000502:physiology; D006801:Humans; D008563:Membrane Lipids / Q000502:physiology; D021962:Membrane Microdomains / Q000502:physiology; D008565:Membrane Proteins / Q000502:physiology; D008954:Models, Biological; D010873:Pinocytosis / Q000502:physiology
D002966:Clathrin; D008563:Membrane Lipids; D008565:Membrane Proteins