Golgi Phosphoprotein 3 Triggers Signal-mediated Incorporation of Glycosyltransferases into Coatomer-coated (COPI) Vesicles |
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Authors: | Elias S P Eckert Ingeborg Reckmann Andrea Hellwig Simone R?hling Assou El-Battari Felix T Wieland Vincent Popoff |
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Institution: | From the ‡Heidelberg University Biochemistry Center (BZH), INF 328 and ;§Interdisciplinary Center for Neurosciences (IZN), INF 364, Heidelberg University, 69120 Heidelberg, Germany and ;¶INSERM UMR 911, Aix-Marseille Université, Centre de Recherche en Oncobiologie et Oncopharmacologie (CR02), 13284 Marseille, France |
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Abstract: | Newly synthesized membrane and secreted proteins undergo a series of posttranslational modifications in the Golgi apparatus, including attachment of carbohydrate moieties. The final structure of so-formed glycans is determined by the order of execution of the different glycosylation steps, which seems intimately related to the spatial distribution of glycosyltransferases and glycosyl hydrolases within the Golgi apparatus. How cells achieve an accurate localization of these enzymes is not completely understood but might involve dynamic processes such as coatomer-coated (COPI) vesicle-mediated trafficking. In yeast, this transport is likely to be regulated by vacuolar protein sorting 74 (Vps74p), a peripheral Golgi protein able to interact with COPI coat as well as with a binding motif present in the cytosolic tails of some mannosyltransferases. Recently, Golgi phosphoprotein 3 (GOLPH3), the mammalian homolog of Vps74, has been shown to control the Golgi localization of core 2 N-acetylglucosamine-transferase 1. Here, we highlight a role of GOLPH3 in the spatial localization of α-2,6-sialyltransferase 1. We show, for the first time, that GOLPH3 supports incorporation of both core 2 N-acetylglucosamine-transferase 1 and α-2,6-sialyltransferase 1 into COPI vesicles. Depletion of GOLPH3 altered the subcellular localization of these enzymes. In contrast, galactosyltransferase, an enzyme that does not interact with GOLPH3, was neither incorporated into COPI vesicles nor was dependent on GOLPH3 for proper localization. |
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Keywords: | COPI Golgi Sialyltransferase Trafficking Vesicles Glycosyltransferases |
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