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Updated: Jul 20, 2026

Pulse-chase Analysis of N-linked Sugar Chains from Glycoproteins in Mammalian Cells
Published on: April 27, 2010
N-linked glycan recognition and processing: the molecular basis of endoplasmic reticulum quality control
Kelley W Moremen1, Maurizio Molinari
1Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602-4712, USA.
Abstract:
Nascent polypeptides emerging into the lumen of the endoplasmic reticulum (ER) are N-glycosylated on asparagines in Asn-Xxx-Ser/Thr motifs. Processing of the core oligosaccharide eventually determines the fate of the associated polypeptide by regulating entry into and retention by the calnexin chaperone system, or extraction from the ER folding environment for disposal. Recent advances have shown that at least two N-glycans are necessary for protein access to the calnexin chaperone system and that polypeptide cycling in the system is a rather rare event, which, for folding-defective polypeptides, is activated only upon persistent misfolding. Additionally, dismantling of the polypeptide-bound N-glycan interrupts futile folding attempts, and elicits preparation of the misfolded chain for dislocation into the cytosol and degradation.
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