title: Clathrin-independent endocytosis: from nonexisting to an extreme degree of complexity.
abstract: Today it is generally accepted that there are several endocytic mechanisms, both the clathrin-dependent one and mechanisms which operate without clathrin and with different requirements when it comes to dynamin, small GTP-binding proteins of the Rho family and specific lipids. It should be noted that clathrin-independent endocytosis can occur even when the cholesterol level in the membrane has been reduced to so low levels that caveolae are gone and clathrin-coated membrane areas are flat. Although new investigators in the field take it for granted that there is a multitude of entry mechanisms, it has taken a long time for this to become accepted. However, more work needs to be done, because one can still ask the question: How many endocytic mechanisms does a cell have, what are their function, and how are they regulated? This article describes some of the history of endocytosis research and attempts to give an overview of the complexity of the mechanisms and their regulation.
authors.affiliation: Centre for Cancer Biomedicine, University of Oslo and Department of Biochemistry, The Norwegian Radium Hospital, Montebello, Oslo, Norway. ksandvig@radium.uio.no
authors.forename: Kirsten
authors.initials: K
authors.lastname: Sandvig
authors.forename: Maria Lyngaas
authors.initials: ML
authors.lastname: Torgersen
authors.forename: Hilde Andersen
authors.initials: HA
authors.lastname: Raa
authors.forename: Bo
authors.initials: B
authors.lastname: van Deurs
mesh_terms: D020727:ADP-Ribosylation Factors / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D021941:Caveolae / Q000378:metabolism; D002966:Clathrin / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology*; D004847:Epithelial Cells / Q000378:metabolism; D006801:Humans; D008563:Membrane Lipids / Q000378:metabolism; D010873:Pinocytosis / Q000502:physiology; D020741:rho GTP-Binding Proteins / Q000378:metabolism
chemical_list: D000199:Actins; D002966:Clathrin; D008563:Membrane Lipids; D020727:ADP-Ribosylation Factors; D020741:rho GTP-Binding Proteins