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Acidic Di-leucine Motif Essential for AP-3–dependent Sorting and Restriction of the Functional Specificity of the Vam3p Vacuolar t-SNARE

The transport of newly synthesized proteins through the vacuolar protein sorting pathway in the budding yeast Saccharomyces cerevisiae requires two distinct target SNAP receptor (t-SNARE) proteins, Pep12p and Vam3p. Pep12p is localized to the pre-vacuolar endosome and its activity is required for tr...

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Detalles Bibliográficos
Autores principales: Darsow, Tamara, Burd, Christopher G., Emr, Scott D.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1998
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2132875/
https://www.ncbi.nlm.nih.gov/pubmed/9722605
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author Darsow, Tamara
Burd, Christopher G.
Emr, Scott D.
author_facet Darsow, Tamara
Burd, Christopher G.
Emr, Scott D.
author_sort Darsow, Tamara
collection PubMed
description The transport of newly synthesized proteins through the vacuolar protein sorting pathway in the budding yeast Saccharomyces cerevisiae requires two distinct target SNAP receptor (t-SNARE) proteins, Pep12p and Vam3p. Pep12p is localized to the pre-vacuolar endosome and its activity is required for transport of proteins from the Golgi to the vacuole through a well defined route, the carboxypeptidase Y (CPY) pathway. Vam3p is localized to the vacuole where it mediates delivery of cargoes from both the CPY and the recently described alkaline phosphatase (ALP) pathways. Surprisingly, despite their organelle-specific functions in sorting of vacuolar proteins, overexpression of VAM3 can suppress the protein sorting defects of pep12Δ cells. Based on this observation, we developed a genetic screen to identify domains in Vam3p (e.g., localization and/or specific protein–protein interaction domains) that allow it to efficiently substitute for Pep12p. Using this screen, we identified mutations in a 7–amino acid sequence in Vam3p that lead to missorting of Vam3p from the ALP pathway into the CPY pathway where it can substitute for Pep12p at the pre-vacuolar endosome. This region contains an acidic di-leucine sequence that is closely related to sorting signals required for AP-3 adaptor–dependent transport in both yeast and mammalian systems. Furthermore, disruption of AP-3 function also results in the ability of wild-type Vam3p to compensate for pep12 mutants, suggesting that AP-3 mediates the sorting of Vam3p via the di-leucine signal. Together, these data provide the first identification of an adaptor protein–specific sorting signal in a t-SNARE protein, and suggest that AP-3–dependent sorting of Vam3p acts to restrict its interaction with compartment-specific accessory proteins, thereby regulating its function. Regulated transport of cargoes such as Vam3p through the AP-3–dependent pathway may play an important role in maintaining the unique composition, function, and morphology of the vacuole.
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spelling pubmed-21328752008-05-01 Acidic Di-leucine Motif Essential for AP-3–dependent Sorting and Restriction of the Functional Specificity of the Vam3p Vacuolar t-SNARE Darsow, Tamara Burd, Christopher G. Emr, Scott D. J Cell Biol Articles The transport of newly synthesized proteins through the vacuolar protein sorting pathway in the budding yeast Saccharomyces cerevisiae requires two distinct target SNAP receptor (t-SNARE) proteins, Pep12p and Vam3p. Pep12p is localized to the pre-vacuolar endosome and its activity is required for transport of proteins from the Golgi to the vacuole through a well defined route, the carboxypeptidase Y (CPY) pathway. Vam3p is localized to the vacuole where it mediates delivery of cargoes from both the CPY and the recently described alkaline phosphatase (ALP) pathways. Surprisingly, despite their organelle-specific functions in sorting of vacuolar proteins, overexpression of VAM3 can suppress the protein sorting defects of pep12Δ cells. Based on this observation, we developed a genetic screen to identify domains in Vam3p (e.g., localization and/or specific protein–protein interaction domains) that allow it to efficiently substitute for Pep12p. Using this screen, we identified mutations in a 7–amino acid sequence in Vam3p that lead to missorting of Vam3p from the ALP pathway into the CPY pathway where it can substitute for Pep12p at the pre-vacuolar endosome. This region contains an acidic di-leucine sequence that is closely related to sorting signals required for AP-3 adaptor–dependent transport in both yeast and mammalian systems. Furthermore, disruption of AP-3 function also results in the ability of wild-type Vam3p to compensate for pep12 mutants, suggesting that AP-3 mediates the sorting of Vam3p via the di-leucine signal. Together, these data provide the first identification of an adaptor protein–specific sorting signal in a t-SNARE protein, and suggest that AP-3–dependent sorting of Vam3p acts to restrict its interaction with compartment-specific accessory proteins, thereby regulating its function. Regulated transport of cargoes such as Vam3p through the AP-3–dependent pathway may play an important role in maintaining the unique composition, function, and morphology of the vacuole. The Rockefeller University Press 1998-08-24 /pmc/articles/PMC2132875/ /pubmed/9722605 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 Articles
Darsow, Tamara
Burd, Christopher G.
Emr, Scott D.
Acidic Di-leucine Motif Essential for AP-3–dependent Sorting and Restriction of the Functional Specificity of the Vam3p Vacuolar t-SNARE
title Acidic Di-leucine Motif Essential for AP-3–dependent Sorting and Restriction of the Functional Specificity of the Vam3p Vacuolar t-SNARE
title_full Acidic Di-leucine Motif Essential for AP-3–dependent Sorting and Restriction of the Functional Specificity of the Vam3p Vacuolar t-SNARE
title_fullStr Acidic Di-leucine Motif Essential for AP-3–dependent Sorting and Restriction of the Functional Specificity of the Vam3p Vacuolar t-SNARE
title_full_unstemmed Acidic Di-leucine Motif Essential for AP-3–dependent Sorting and Restriction of the Functional Specificity of the Vam3p Vacuolar t-SNARE
title_short Acidic Di-leucine Motif Essential for AP-3–dependent Sorting and Restriction of the Functional Specificity of the Vam3p Vacuolar t-SNARE
title_sort acidic di-leucine motif essential for ap-3–dependent sorting and restriction of the functional specificity of the vam3p vacuolar t-snare
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2132875/
https://www.ncbi.nlm.nih.gov/pubmed/9722605
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