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Updated: Jun 19, 2026

Identification and Characterization of Protein Glycosylation using Specific Endo- and Exoglycosidases
Published on: December 26, 2011
Chemical approaches toward understanding glycan-mediated protein quality control
Yoichi Takeda1, Kiichiro Totani, Ichiro Matsuo
1RIKEN Advance Science Institute, Wako, Saitama 351-0198, Japan.
Abstract:
High-mannose-type oligosaccharides, which are cotranslationally introduced to nascent polypeptides during N-glycosylation, play critical roles in protein quality control. Involved in this process are a number of intracellular carbohydrate-recognizing proteins or carbohydrate-processing enzymes, including calnexin/calreticulin, malectin, glucosidase I (G-I) and II (G-II), UDP-glucose:glycoprotein glucosyltransferase (UGGT), cargo receptors (VIP36, ERGL, and ERGIC-53), ER 1,2-mannosidase I, ER degradation-enhancing alpha-mannosidase-like proteins (EDEMs) and ubiquitin ligase. Although all these proteins seem to recognize high-mannose glycans, their precise specificities are yet to be clarified. In order to conduct quantitative evaluation of the activity and specificity of these proteins, a comprehensive set of high-mannose-type glycans and their variously functionalized derivatives were synthesized and used to analyze enzymes involved in glycoprotein quality control system.
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