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Pulse-chase Analysis of N-linked Sugar Chains from Glycoproteins in Mammalian Cells
Published on: April 27, 2010
Dissecting glycoprotein quality control in the secretory pathway
C M Cabral1, Y Liu, R N Sifers
1Dept of Pathology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
Trends in Biochemical Sciences
|October 9, 2001
Summary
Misfolded glycoproteins are eliminated from the endoplasmic reticulum via a glycan-based disposal system. This conserved pathway ensures proper protein folding and cellular differentiation in eukaryotes.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Asparagine-linked glycosylation is crucial for polypeptide folding in the early secretory pathway.
- The endoplasmic reticulum employs conformation-based quality control to eliminate misfolded glycoproteins.
- Oligosaccharide-processing enzymes and lectins interact with glycans to target defective glycoproteins.
Purpose of the Study:
- To investigate the role of the glycan-based disposal system in protein quality control.
- To understand how transport-defective glycoproteins are selectively eliminated from the secretory pathway.
- To explore the link between glycoprotein degradation mechanisms and cellular differentiation.
Main Methods:
- Analysis of oligosaccharide-processing enzymes and lectins involved in glycoprotein quality control.
- Investigating the mechanisms of glycoprotein substrate recruitment for degradation.
- Studying the role of asparagine-linked glycans in targeting misfolded proteins.
Main Results:
- A conserved glycan-based disposal system acts as a terminal checkpoint in eukaryote gene expression.
- Specific enzymes and lectins utilize the asparagine-linked glycan to remove transport-defective glycoproteins.
- Divergent mechanisms for glycoprotein substrate recruitment highlight a role in cellular differentiation.
Conclusions:
- The glycan-based disposal system is essential for maintaining protein homeostasis in the early secretory pathway.
- This system represents an evolutionarily conserved mechanism for controlling protein folding and function.
- Variations in glycoprotein degradation pathways contribute to cellular differentiation in higher eukaryotes.
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