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André Verbert - One of the best experts on this subject based on the ideXlab platform.
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Transport of free and N-linked oligomannoside species across the Rough Endoplasmic Reticulum membranes.
Glycobiology, 2000Co-Authors: René Cacan, André VerbertAbstract:The N-glycosylation process occurs in the Rough Endoplasmic Reticulum. It requires the transport of glycosyl donors into the lumen and the exit of the glycosylated products toward the secretory pathway. Besides this main flow, the formation of free oligomannosides, glycopeptides, and misfolded glycoproteins which do not enter the secretory pathway and are cleared out of the Endoplasmic Reticulum by specific transports has been demonstrated. This review focuses on the export mechanisms of these three side products of the N-glycosylation process and discusses their physiological significance.
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Trafficking of oligomannosides released during N-glycosylation: a clearing mechanism of the Rough Endoplasmic Reticulum
Biochimica et Biophysica Acta (BBA) - General Subjects, 1999Co-Authors: André Verbert, René CacanAbstract:Abstract The main reaction of N-glycosylation of proteins is the transfer ‘en bloc’ of the oligosaccharide moieties of lipid intermediates to an asparagine residue of the nascent protein. For the past 15 years, a few laboratories including ours have shown that the process was accompanied by the release of oligosaccharide-phosphates and of neutral oligosaccharides possessing one GlcNAc (OS-Gn1) or two GlcNAc (OS-Gn2) at the reducing end. The aim of this review is to gather the evidence for the different origins of these soluble oligomannosides, to examine their subcellular location and intracellular trafficking. Furthermore, using Brefeldin A we demonstrated that this released oligomannoside material could be the substrate for the Golgi glycosidases and glycosyltransferases. Indeed, released oligomannoside never reach the Golgi vesicles either because they are directly produced in the cytosol as has been demonstrated for oligosaccharide-phosphates and for neutral oligosaccharides possessing one GlcNAc at the reducing end or because they are actively transported out of the Rough Endoplasmic Reticulum to the cytosol. One of the functions of oligomannoside trafficking between Rough Endoplasmic Reticulum, cytosol and lysosomes could be to prevent these oligosaccharides for competing with glycosylation in the Golgi.
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Retention and Degradation of N-Glycoproteins in the Rough Endoplasmic Reticulum
Bioscience Reports, 1999Co-Authors: Sandrine Duvet, Jean Dubuisson, Myriam Ermonval, René Cacan, André VerbertAbstract:Recent studies have shown that newly synthesized proteins and glycoproteins are submitted to a quality control mechanism in the Rough Endoplasmic Reticulum (ER). In this report we present two models: One model will illustrate a transient retention in Rough ER leading to a further degradation of glycoproteins in the cytosol, (soluble alkaline phosphatase expressed in Man-P-Dol deficient CHO cells lines). The second model will illustrate a strict retention of glycoproteins in Rough ER without degradation nor recycling thRough the Golgi (E1, E2 glycoproteins of Hepatitis C virus in stably transfected UHCV-11.4 cells and in infected Hep G2 cells).
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retention and degradation of n glycoproteins in the Rough Endoplasmic Reticulum
Bioscience Reports, 1999Co-Authors: Sandrine Duvet, Jean Dubuisson, Myriam Ermonval, René Cacan, André VerbertAbstract:Recent studies have shown that newly synthesized proteins and glycoproteins are submitted to a quality control mechanism in the Rough Endoplasmic Reticulum (ER). In this report we present two models: One model will illustrate a transient retention in Rough ER leading to a further degradation of glycoproteins in the cytosol, (soluble alkaline phosphatase expressed in Man-P-Dol deficient CHO cells lines). The second model will illustrate a strict retention of glycoproteins in Rough ER without degradation nor recycling thRough the Golgi (E1, E2 glycoproteins of Hepatitis C virus in stably transfected UHCV-11.4 cells and in infected Hep G2 cells). In both cases, oligomannoside structures are markers of these phenomena, either as free soluble released oligomannosides in the case of degradation, or as N-linked oligomannosides for strict retention in Rough ER.
W. A. Dunn - One of the best experts on this subject based on the ideXlab platform.
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Effects of streptozotocin-induced diabetes on Rough Endoplasmic Reticulum and lysosomes of rat liver.
American Journal of Physiology-Endocrinology and Metabolism, 1992Co-Authors: S. E. Lenk, D. Bhat, W. Blakeney, W. A. DunnAbstract:In the absence of amino acids and insulin, ribosome-free regions of the Rough Endoplasmic Reticulum (RER) invaginate to form an autophagosome, which matures into an autolysosome (W. A. Dunn, Jr., J...
René Cacan - One of the best experts on this subject based on the ideXlab platform.
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Transport of free and N-linked oligomannoside species across the Rough Endoplasmic Reticulum membranes.
Glycobiology, 2000Co-Authors: René Cacan, André VerbertAbstract:The N-glycosylation process occurs in the Rough Endoplasmic Reticulum. It requires the transport of glycosyl donors into the lumen and the exit of the glycosylated products toward the secretory pathway. Besides this main flow, the formation of free oligomannosides, glycopeptides, and misfolded glycoproteins which do not enter the secretory pathway and are cleared out of the Endoplasmic Reticulum by specific transports has been demonstrated. This review focuses on the export mechanisms of these three side products of the N-glycosylation process and discusses their physiological significance.
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Trafficking of oligomannosides released during N-glycosylation: a clearing mechanism of the Rough Endoplasmic Reticulum
Biochimica et Biophysica Acta (BBA) - General Subjects, 1999Co-Authors: André Verbert, René CacanAbstract:Abstract The main reaction of N-glycosylation of proteins is the transfer ‘en bloc’ of the oligosaccharide moieties of lipid intermediates to an asparagine residue of the nascent protein. For the past 15 years, a few laboratories including ours have shown that the process was accompanied by the release of oligosaccharide-phosphates and of neutral oligosaccharides possessing one GlcNAc (OS-Gn1) or two GlcNAc (OS-Gn2) at the reducing end. The aim of this review is to gather the evidence for the different origins of these soluble oligomannosides, to examine their subcellular location and intracellular trafficking. Furthermore, using Brefeldin A we demonstrated that this released oligomannoside material could be the substrate for the Golgi glycosidases and glycosyltransferases. Indeed, released oligomannoside never reach the Golgi vesicles either because they are directly produced in the cytosol as has been demonstrated for oligosaccharide-phosphates and for neutral oligosaccharides possessing one GlcNAc at the reducing end or because they are actively transported out of the Rough Endoplasmic Reticulum to the cytosol. One of the functions of oligomannoside trafficking between Rough Endoplasmic Reticulum, cytosol and lysosomes could be to prevent these oligosaccharides for competing with glycosylation in the Golgi.
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Retention and Degradation of N-Glycoproteins in the Rough Endoplasmic Reticulum
Bioscience Reports, 1999Co-Authors: Sandrine Duvet, Jean Dubuisson, Myriam Ermonval, René Cacan, André VerbertAbstract:Recent studies have shown that newly synthesized proteins and glycoproteins are submitted to a quality control mechanism in the Rough Endoplasmic Reticulum (ER). In this report we present two models: One model will illustrate a transient retention in Rough ER leading to a further degradation of glycoproteins in the cytosol, (soluble alkaline phosphatase expressed in Man-P-Dol deficient CHO cells lines). The second model will illustrate a strict retention of glycoproteins in Rough ER without degradation nor recycling thRough the Golgi (E1, E2 glycoproteins of Hepatitis C virus in stably transfected UHCV-11.4 cells and in infected Hep G2 cells).
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retention and degradation of n glycoproteins in the Rough Endoplasmic Reticulum
Bioscience Reports, 1999Co-Authors: Sandrine Duvet, Jean Dubuisson, Myriam Ermonval, René Cacan, André VerbertAbstract:Recent studies have shown that newly synthesized proteins and glycoproteins are submitted to a quality control mechanism in the Rough Endoplasmic Reticulum (ER). In this report we present two models: One model will illustrate a transient retention in Rough ER leading to a further degradation of glycoproteins in the cytosol, (soluble alkaline phosphatase expressed in Man-P-Dol deficient CHO cells lines). The second model will illustrate a strict retention of glycoproteins in Rough ER without degradation nor recycling thRough the Golgi (E1, E2 glycoproteins of Hepatitis C virus in stably transfected UHCV-11.4 cells and in infected Hep G2 cells). In both cases, oligomannoside structures are markers of these phenomena, either as free soluble released oligomannosides in the case of degradation, or as N-linked oligomannosides for strict retention in Rough ER.
Lawrence D. F. Moon - One of the best experts on this subject based on the ideXlab platform.
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Chromatolysis: Do injured axons regenerate poorly when ribonucleases attack Rough Endoplasmic Reticulum, ribosomes and RNA?
Developmental Neurobiology, 2018Co-Authors: Lawrence D. F. MoonAbstract:After axonal injury, chromatolysis (fragmentation of Nissl substance) can occur in the soma. Electron microscopy shows that chromatolysis involves fission of the Rough Endoplasmic Reticulum. In CNS neurons (which do not regenerate axons back to their original targets) or in motor neurons or dorsal root ganglion neurons denied axon regeneration (e.g., by transection and ligation), chromatolysis is often accompanied by degranulation (loss of ribosomes from Rough Endoplasmic Reticulum), disaggregation of polyribosomes and degradation of monoribosomes into dust-like particles. Ribosomes and Rough Endoplasmic Reticulum may also be degraded in autophagic vacuoles by ribophagy and reticulophagy, respectively. In other words, chromatolysis is disruption of parts of the protein synthesis infrastructure. Whereas some neurons may show transient or no chromatolysis, severely injured neurons can remain chromatolytic and never again synthesize normal levels of protein; some may atrophy or die. Ribonuclease(s) might cause the following features of chromatolysis: fragmentation and degranulation of Rough Endoplasmic Reticulum, disaggregation of polyribosomes and degradation of monoribosomes. For example, ribonucleases in the EndoU/PP11 family can modify Rough Endoplasmic Reticulum; many ribonucleases can degrade mRNA causing polyribosomes to unchain and disperse, and they can disassemble monoribosomes; Ribonuclease 5 can control rRNA synthesis and degrade tRNA; Ribonuclease T2 can degrade ribosomes, Endoplasmic Reticulum and RNA within autophagic vacuoles; and Ribonuclease IRE1α acts as a stress sensor within the Endoplasmic Reticulum. Regeneration might be improved after axonal injury by protecting the protein synthesis machinery from catabolism; targeting ribonucleases using inhibitors can enhance neurite outgrowth and could be a profitable strategy in vivo. © 2018 Wiley Periodicals, Inc. Develop Neurobiol, 2018.
Jong-sang Park - One of the best experts on this subject based on the ideXlab platform.
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Characterization of the ATP transporter in the reconstituted Rough Endoplasmic Reticulum proteoliposomes
Biochimica et Biophysica Acta (BBA) - Biomembranes, 2000Co-Authors: Seung Jin Shin, Woo Kyoung Lee, Hyung Wook Lim, Jong-sang ParkAbstract:AbstractAdenosine triphosphate (ATP) transporter from rat liver Rough Endoplasmic Reticulum (RER) was solubilized and reconstituted into phosphatidylcholine liposomes. The RER proteoliposomes, resulting from optimizing some reconstitution parameters, had an apparent Km value of 1.5 μM and a Vmax of 286 pmol min−1 (mg protein)−1 and showed higher affinity for ATP and a lower Vmax value than intact RER (Km of 6.5 μM and Vmax of 1 nmol). ATP transport was time- and temperature-dependent, inhibited by 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid, which is known as an inhibitor of anion transporters including ATP transporter, but was not affected by atractyloside, a specific inhibitor of mitochondrial ADP/ATP carrier. The internal and external effects of various nucleotides on the ATP transport were examined. ATP transport was cis-inhibited strongly by ADP and weakly by AMP. ADP-preloaded RER proteoliposomes showed a specific increase of ATP transport activity while AMP-preloaded RER proteoliposomes did not show the enhanced overshoot peak in the ATP uptake plot. These results demonstrate the ADP/ATP antiport mechanism of ATP transport in rat liver RER
