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Is movement of mannose 6-phosphate-specific receptor triggered by binding of lysosomal enzymes?

Mannose 6-phosphate-specific receptors with an apparent molecular mass of 215,000 are present in fibroblasts at the cell surface and in intracellular membranes. The cell surface receptors mediate endocytosis of exogenous lysosomal enzymes and exchange with the intracellular receptors, which function...

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Detalles Bibliográficos
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1987
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2114508/
https://www.ncbi.nlm.nih.gov/pubmed/2953746
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description Mannose 6-phosphate-specific receptors with an apparent molecular mass of 215,000 are present in fibroblasts at the cell surface and in intracellular membranes. The cell surface receptors mediate endocytosis of exogenous lysosomal enzymes and exchange with the intracellular receptors, which function in the sorting of endogenous lysosomal enzymes. In the present study, several methods independent of receptor ligands were designed in order to examine the exchange of receptors under conditions where receptor-ligand complexes do not dissociate (weak bases and monensin) or where receptor-ligand complexes are not formed due to absence of endogenous ligands as a result of inhibition of protein synthesis. Weak bases and monensin reduce the concentration of receptors at the cell surface by 20-30% and free cell surface receptors were replaced by occupied receptors. The latter continued to be exchanged with internal ligand-occupied receptors and the rates of the exchange were similar to the control values. The exchange of receptors between the cell surface and internal membranes was also not affected when the receptor ligands were depleted from the transport compartments by treating the cells with cycloheximide for up to 10 h. We conclude from these results that movement of mannose 6-phosphate- specific receptors along the endocytosis and sorting pathways is constitutive and not triggered by binding or dissociation of ligands.
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spelling pubmed-21145082008-05-01 Is movement of mannose 6-phosphate-specific receptor triggered by binding of lysosomal enzymes? J Cell Biol Articles Mannose 6-phosphate-specific receptors with an apparent molecular mass of 215,000 are present in fibroblasts at the cell surface and in intracellular membranes. The cell surface receptors mediate endocytosis of exogenous lysosomal enzymes and exchange with the intracellular receptors, which function in the sorting of endogenous lysosomal enzymes. In the present study, several methods independent of receptor ligands were designed in order to examine the exchange of receptors under conditions where receptor-ligand complexes do not dissociate (weak bases and monensin) or where receptor-ligand complexes are not formed due to absence of endogenous ligands as a result of inhibition of protein synthesis. Weak bases and monensin reduce the concentration of receptors at the cell surface by 20-30% and free cell surface receptors were replaced by occupied receptors. The latter continued to be exchanged with internal ligand-occupied receptors and the rates of the exchange were similar to the control values. The exchange of receptors between the cell surface and internal membranes was also not affected when the receptor ligands were depleted from the transport compartments by treating the cells with cycloheximide for up to 10 h. We conclude from these results that movement of mannose 6-phosphate- specific receptors along the endocytosis and sorting pathways is constitutive and not triggered by binding or dissociation of ligands. The Rockefeller University Press 1987-06-01 /pmc/articles/PMC2114508/ /pubmed/2953746 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
Is movement of mannose 6-phosphate-specific receptor triggered by binding of lysosomal enzymes?
title Is movement of mannose 6-phosphate-specific receptor triggered by binding of lysosomal enzymes?
title_full Is movement of mannose 6-phosphate-specific receptor triggered by binding of lysosomal enzymes?
title_fullStr Is movement of mannose 6-phosphate-specific receptor triggered by binding of lysosomal enzymes?
title_full_unstemmed Is movement of mannose 6-phosphate-specific receptor triggered by binding of lysosomal enzymes?
title_short Is movement of mannose 6-phosphate-specific receptor triggered by binding of lysosomal enzymes?
title_sort is movement of mannose 6-phosphate-specific receptor triggered by binding of lysosomal enzymes?
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2114508/
https://www.ncbi.nlm.nih.gov/pubmed/2953746