Glycosphingolipid-enriched, detergent-insoluble complexes in protein sorting in epithelial cells.
In simple epithelial cells, the delivery of apical and basolateral proteins to the cell surface is mediated by sorting in the trans-Golgi network and transport via separate vesicular carriers. In order to identify the molecular machinery involved in protein sorting, we have recently studied a detergent-insoluble complex in Madin-Darby canine kidney (MDCK) cells, following CHAPS extraction of exocytic carrier vesicles, specifically including the apical marker protein influenza hemagglutinin (HA). Previously, a Triton X-100 insoluble membrane residue that was enriched in glycosylphosphatidylinositol-anchored (GPI) proteins and glycolipids was characterized and implicated in transport to the apical cell surface [Brown, D., & Rose, J. (1991) Cell 68, 533-544]. In this report, the protein compositions of the CHAPS and Triton complexes have been compared by two-dimensional gel analysis. Only a few major membrane proteins are found in the complexes. The protein compositions are qualitatively similar, but differ quantitatively in the individual components. The CHAPS complex is depleted of GPI-linked proteins and retains a minor fraction of lipids similar in composition to that of the Triton X-100 insoluble complex. We propose that in vivo the complexes form part of a sorting platform that mediates protein segregation and delivery to the apical cell surface.
Cell Biology Programme, European Molecular Biology Laboratory, Heidelberg, Germany.
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Fiedler
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Kobayashi
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Kurzchalia
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Simons
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002793:Cholic Acids; D003902:Detergents; D004285:Dogs; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D004848:Epithelium / Q000378:metabolism; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D007668:Kidney; D008715:Methionine / Q000378:metabolism; D017830:Octoxynol; D015388:Organelles / Q000378:metabolism; D011092:Polyethylene Glycols; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational; D011506:Proteins / Q000302:isolation & purification; D013462:Sulfur Radioisotopes
D002793:Cholic Acids; D003902:Detergents; D017261:Glycosylphosphatidylinositols; D011506:Proteins; D013462:Sulfur Radioisotopes; D011092:Polyethylene Glycols; D017830:Octoxynol; C010615:Nonidet P-40; D008715:Methionine; C028213:3-((3-cholamidopropyl)dimethylammonium)-1-propanesulfonate