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Updated: Jul 9, 2025

Using Caenorhabditis elegans to Screen for Tissue-Specific Chaperone Interactions
Published on: June 7, 2020
ER chaperones use a protein folding and quality control glyco-code
Kevin P Guay1, Haiping Ke2, Nathan P Canniff1
1Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, MA, USA; Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, MA, USA.
The glyco-code, or N-glycan features, guides protein folding and quality control in the endoplasmic reticulum. Specific glycan patterns dictate chaperone interactions for serpins like alpha-1 antitrypsin and antithrombin III maturation.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- N-glycans function as crucial quality control signals in the endoplasmic reticulum, recruiting lectin chaperones for protein maturation.
- The spatial arrangement and composition of N-glycans, termed the glyco-code, are critical determinants in the selection of appropriate chaperones.
- Serpins (serine protease inhibitors) are known for their non-sequential folding pathways, leading to metastable active conformations.
Purpose of the Study:
- To investigate the role of the N-glycan glyco-code in the maturation and quality control of human serpins, specifically alpha-1 antitrypsin (AAT) and antithrombin III (ATIII).
- To elucidate how glycan position and composition influence chaperone interactions and protein folding pathways in serpins.
Main Methods:
- Comparative analysis of N-glycan distribution and chaperone interactions for AAT and ATIII.
- Investigation of the role of UGGT (UDP-glucose glycoprotein glucosyltransferase) in the quality control of serpin variants.
- Characterization of glycan-mediated chaperone selection during protein folding.
Main Results:
- AAT, with N-terminal glycans, benefits from early lectin chaperone engagement.
- ATIII, possessing more C-terminal glycans, initially interacts with BiP before lectin chaperones are recruited via UGGT-mediated reglucosylation.
- UGGT activity is elevated for misfolding-prone serpin disease variants, with preferential glucosylation occurring on the C-terminal glycan.
Conclusions:
- The presence, position, and composition of N-glycans (glyco-code) are integral to directing the proper folding, quality control, and trafficking of serpins.
- Serpins leverage their specific glyco-code to navigate the endoplasmic reticulum quality control system effectively.
- Differential glycan positioning dictates distinct chaperone engagement strategies for serpin maturation.
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