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Integral Membrane Protein Sorting to Vacuoles in Plant Cells: Evidence for Two Pathways

Plant cells may contain two functionally distinct vacuolar compartments. Membranes of protein storage vacuoles (PSV) are marked by the presence of α-tonoplast intrinsic protein (TIP), whereas lytic vacuoles (LV) are marked by the presence of γ-TIP. Mechanisms for sorting integral membrane proteins t...

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Detalles Bibliográficos
Autores principales: Jiang, Liwen, Rogers, John C.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1998
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2133091/
https://www.ncbi.nlm.nih.gov/pubmed/9832548
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author Jiang, Liwen
Rogers, John C.
author_facet Jiang, Liwen
Rogers, John C.
author_sort Jiang, Liwen
collection PubMed
description Plant cells may contain two functionally distinct vacuolar compartments. Membranes of protein storage vacuoles (PSV) are marked by the presence of α-tonoplast intrinsic protein (TIP), whereas lytic vacuoles (LV) are marked by the presence of γ-TIP. Mechanisms for sorting integral membrane proteins to the different vacuoles have not been elucidated. Here we study a chimeric integral membrane reporter protein expressed in tobacco suspension culture protoplasts whose traffic was assessed biochemically by following acquisition of complex Asn-linked glycan modifications and proteolytic processing, and whose intracellular localization was determined with confocal immunofluorescence. We show that the transmembrane domain of the plant vacuolar sorting receptor BP-80 directs the reporter protein via the Golgi to the LV prevacuolar compartment, and attaching the cytoplasmic tail (CT) of γ-TIP did not alter this traffic. In contrast, the α-TIP CT prevented traffic of the reporter protein through the Golgi and caused it to be localized in organelles separate from ER and from Golgi and LV prevacuolar compartment markers. These organelles had a buoyant density consistent with vacuoles, and α-TIP protein colocalized in them with the α-TIP CT reporter protein when the two were expressed together in protoplasts. These results are consistent with two separate pathways to vacuoles for membrane proteins: a direct ER to PSV pathway, and a separate pathway via the Golgi to the LV.
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spelling pubmed-21330912008-05-01 Integral Membrane Protein Sorting to Vacuoles in Plant Cells: Evidence for Two Pathways Jiang, Liwen Rogers, John C. J Cell Biol Article Plant cells may contain two functionally distinct vacuolar compartments. Membranes of protein storage vacuoles (PSV) are marked by the presence of α-tonoplast intrinsic protein (TIP), whereas lytic vacuoles (LV) are marked by the presence of γ-TIP. Mechanisms for sorting integral membrane proteins to the different vacuoles have not been elucidated. Here we study a chimeric integral membrane reporter protein expressed in tobacco suspension culture protoplasts whose traffic was assessed biochemically by following acquisition of complex Asn-linked glycan modifications and proteolytic processing, and whose intracellular localization was determined with confocal immunofluorescence. We show that the transmembrane domain of the plant vacuolar sorting receptor BP-80 directs the reporter protein via the Golgi to the LV prevacuolar compartment, and attaching the cytoplasmic tail (CT) of γ-TIP did not alter this traffic. In contrast, the α-TIP CT prevented traffic of the reporter protein through the Golgi and caused it to be localized in organelles separate from ER and from Golgi and LV prevacuolar compartment markers. These organelles had a buoyant density consistent with vacuoles, and α-TIP protein colocalized in them with the α-TIP CT reporter protein when the two were expressed together in protoplasts. These results are consistent with two separate pathways to vacuoles for membrane proteins: a direct ER to PSV pathway, and a separate pathway via the Golgi to the LV. The Rockefeller University Press 1998-11-30 /pmc/articles/PMC2133091/ /pubmed/9832548 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Article
Jiang, Liwen
Rogers, John C.
Integral Membrane Protein Sorting to Vacuoles in Plant Cells: Evidence for Two Pathways
title Integral Membrane Protein Sorting to Vacuoles in Plant Cells: Evidence for Two Pathways
title_full Integral Membrane Protein Sorting to Vacuoles in Plant Cells: Evidence for Two Pathways
title_fullStr Integral Membrane Protein Sorting to Vacuoles in Plant Cells: Evidence for Two Pathways
title_full_unstemmed Integral Membrane Protein Sorting to Vacuoles in Plant Cells: Evidence for Two Pathways
title_short Integral Membrane Protein Sorting to Vacuoles in Plant Cells: Evidence for Two Pathways
title_sort integral membrane protein sorting to vacuoles in plant cells: evidence for two pathways
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2133091/
https://www.ncbi.nlm.nih.gov/pubmed/9832548
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