Abstract
Newly synthesized apical and basolateral membrane proteins are sorted from one another in polarized epithelial cells. The trans-Golgi network participates in this sorting process, but some basolateral proteins travel from the Golgi to recycling endosomes (REs) before their surface delivery. Using a novel system for pulse-chase microscopy, we have visualized the postsynthetic route pursued by a newly synthesized cohort of Na,K-ATPase. We find that the basolateral delivery of newly synthesized Na,K-ATPase occurs via a pathway distinct from that pursued by the vesicular stomatitis virus G protein (VSV-G). Na,K-ATPase surface delivery occurs at a faster rate than that observed for VSV-G. The Na,K-ATPase does not pass through the RE compartment en route to the plasma membrane, and Na,K-ATPase trafficking is not regulated by the same small GTPases as other basolateral proteins. Finally, Na,K-ATPase and VSV-G travel in separate post-Golgi transport intermediates, demonstrating directly that multiple routes exist for transport from the Golgi to the basolateral membrane in polarized epithelial cells.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Biological Transport / physiology
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Cadherins / metabolism
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Cell Line
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Cell Membrane / metabolism*
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Cell Polarity*
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Dogs
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Endosomes / metabolism
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Epithelial Cells* / cytology
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Epithelial Cells* / metabolism
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Exocytosis / physiology
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Golgi Apparatus / metabolism
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Humans
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Membrane Glycoproteins / chemistry
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Membrane Glycoproteins / genetics
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Membrane Glycoproteins / metabolism
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Membrane Proteins / chemistry
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Membrane Proteins / genetics
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Membrane Proteins / metabolism*
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Models, Molecular
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Protein Structure, Secondary
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Protein Transport / physiology
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Receptors, Transferrin / genetics
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Receptors, Transferrin / metabolism
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Sodium-Potassium-Exchanging ATPase / chemistry
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Sodium-Potassium-Exchanging ATPase / genetics
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Sodium-Potassium-Exchanging ATPase / metabolism
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Staining and Labeling / methods
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Viral Envelope Proteins / chemistry
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Viral Envelope Proteins / genetics
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Viral Envelope Proteins / metabolism
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trans-Golgi Network / metabolism
Substances
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Cadherins
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G protein, vesicular stomatitis virus
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Membrane Glycoproteins
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Membrane Proteins
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Receptors, Transferrin
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Recombinant Fusion Proteins
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Viral Envelope Proteins
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Sodium-Potassium-Exchanging ATPase