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Accurately measuring the ability of the K/HDEL receptor (ERD2) to retain the ER cargo Amy-HDEL has questioned earlier results on which the popular receptor recycling model is based upon. Here we demonstrate that ERD2 Golgi-retention, rather than fast ER export supports its function. Ligand-induced ERD2 redistribution is only observed when the C-terminus is masked or mutated, compromising the signal that prevents Golgi-to-ER transport of the receptor. Forcing COPI mediated retrograde transport destroys receptor function, but introducing ER-to-Golgi export or cis-Golgi retention signals re-activate ERD2 when its endogenous Golgi-retention signal is masked or deleted. We propose that ERD2 remains fixed as a Golgi gatekeeper, capturing K/HDEL proteins when they arrive and releasing them again into a subdomain for retrograde transport back to the ER. An in vivo ligand:receptor ratio far greater than 100 to 1 strongly supports this model, and the underlying mechanism appears to be extremely conserved across kingdoms.
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http://dx.doi.org/10.1038/s41467-023-37056-0 | DOI Listing |
Nat Commun
March 2023
Centre for Plant Sciences, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK.
Accurately measuring the ability of the K/HDEL receptor (ERD2) to retain the ER cargo Amy-HDEL has questioned earlier results on which the popular receptor recycling model is based upon. Here we demonstrate that ERD2 Golgi-retention, rather than fast ER export supports its function. Ligand-induced ERD2 redistribution is only observed when the C-terminus is masked or mutated, compromising the signal that prevents Golgi-to-ER transport of the receptor.
View Article and Find Full Text PDFPLoS One
September 2020
Molecular and Cell Biology, Department of Biosciences and Center of Human and Molecular Biology (ZHMB), Saarland University, Saarbrücken, Germany.
In eukaryotic cells, KDEL receptors (KDELRs) facilitate the retrieval of endoplasmic reticulum (ER) luminal proteins from the Golgi compartment back to the ER. Apart from the well-documented retention function, recent findings reveal that the cellular KDELRs have more complex roles, e.g.
View Article and Find Full Text PDFENDOMEMBRANE PROTEIN 70 (EMP70) proteins constitute a 12-member superfamily in Arabidopsis thaliana, and are the most abundant protein species in plant Golgi proteomes. However, the physiological functions of EMPs in plants remain largely unknown. Here we have demonstrated that two AtEMP12 T-DNA insertion mutants are sensitive to ER (endoplasmic reticulum) stress as induced by tunicamycin and dithiothreitol treatments.
View Article and Find Full Text PDFPlant Cell
September 2018
Centre for Plant Sciences, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
Accumulation of soluble proteins in the endoplasmic reticulum (ER) of plants is mediated by a receptor termed ER RETENTION DEFECTIVE2 (ERD2) or K/HDEL receptor. Using two gain-of-function assays and by complementing loss of function in , we discovered that compromising the lumenal N terminus or the cytosolic C terminus with fluorescent fusions abolishes its biological function and profoundly affects its subcellular localization. Based on the confirmed asymmetrical topology of ERD2, we engineered a new fluorescent ERD2 fusion protein that retains biological activity.
View Article and Find Full Text PDFJ Cell Sci
January 2018
Departamento de Bioquímica y Biología Molecular, Estructura de Recerca Interdisciplinar en Biotecnología i Biomedicina (ERI BIOTECMED), Facultat de Farmacia, Universitat de València, E-46100 Burjassot (Valencia), Spain
The p24 family of proteins (also known as the TMED family) are key regulators of protein trafficking along the secretory pathway, but very little is known about their functions in plants. A quadruple loss-of-function mutant affecting the p24 genes from the δ-1 subclass of the p24δ subfamily () showed alterations in the Golgi, suggesting that these p24 proteins play a role in the organization of the compartments of the early secretory pathway in Loss of p24δ-1 proteins also induced the accumulation of the K/HDEL receptor ERD2a (ER lumen protein-retaining receptor A) at the Golgi and increased secretion of BiP family proteins, ER chaperones containing an HDEL signal, probably due to an inhibition of COPI-dependent Golgi-to-ER transport of ERD2a and thus retrieval of K/HDEL ligands. Although the mutant showed enhanced sensitivity to salt stress, it did not show obvious phenotypic alterations under standard growth conditions.
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