Glycosylation in the endoplasmic reticulum (ER) is closely associated with protein folding and quality control. We recently described a non-canonical ER quality control mechanism for folding of thrombospondin type 1 repeats by Protein O-fucosyltransferase 2 (POFUT2). Epidermal Growth Factor-like (EGF) repeats are also small, cysteine rich protein motifs that can be O-glycosylated by several ER-localized enzymes including Protein O-glucosyltransferase 1 (POGLUT1) and POFUT1. Both POGLUT1 and POFUT1 modify the Notch receptor on multiple EGF repeats and are essential for full Notch function. The fact that POGLUT1 and POFUT1 can distinguish between folded and unfolded EGF repeats raised the possibility that they participate in a quality control pathway for folding of EGF repeats in proteins such as Notch. Here we demonstrate that cell-surface expression of endogenous Notch1 in HEK293T cells is dependent on the presence of POGLUT1 and POFUT1 in an additive manner. In vitro unfolding assays reveal that addition of O-glucose or O-fucose stabilizes a single EGF repeat, and that addition of both O-glucose and O-fucose enhances stability in an additive manner. Finally, we solved the crystal structure of a single EGF repeat covalently modified by a full O-glucose trisaccharide at 2.2 Å resolution. The structure reveals that the glycan fills up a surface groove of the EGF with multiple contacts with the protein, providing a chemical basis for the stabilizing effects of the glycans. Taken together, this work suggests that O-fucose and O-glucose glycans cooperatively stabilize individual EGF repeats through intramolecular interactions, thereby regulating Notch trafficking in cells.
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Publication date: Available online 4 January 2018 Source: European Journal of Radiology Author(s): Peiyao Zhang, Jing Wang, Qin Xu, Zhen...
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Publication date: March 2017 Source: Free Radical Biology and Medicine, Volume 104 from #AlexandrosSfakianakis via Alexandros G.Sfak...
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Deepak Thapa, Vanita Ahuja, Deepanshu Dhiman Indian Journal of Anaesthesia 2017 61(12):1012-1014 from #AlexandrosSfakianakis via Alexa...
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BACKGROUND AND PURPOSE: Dengue is a common arboviral disease, which uncommonly involves the brain. There has been a recent surge in dengu...
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Linked Article: Maintz et al. Br J Dermatol 2017; 176:481–487 . from #AlexandrosSfakianakis via Alexandros G.Sfakianakis on Inoreader h...
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Publication date: Available online 28 February 2018 Source: Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology Author(s): Mo...
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