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09:54
Identification and Characterization of Protein Glycosylation using Specific Endo- and Exoglycosidases
Published on: December 26, 2011
A cytoplasmic peptide: N-glycanase
Kaori Tanabe1, William J Lennarz, Tadashi Suzuki
1Department of Biochemistry, Osaka University, Graduate School of Medicine, Japan.
Methods in Enzymology
|November 23, 2006
Summary
Cytoplasmic peptide:N-glycanase (PNGase) aids proteasomal degradation of misfolded glycoproteins. Assays monitoring deglycosylation and charge changes detect PNGase activity in vitro and in vivo.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Cytoplasmic peptide:N-glycanase (PNGase) is involved in degrading aberrant glycoproteins from the endoplasmic reticulum.
- PNGase action is crucial for proteasomal degradation, as N-glycan removal facilitates protein entry into the proteasome.
- Deglycosylation by PNGase removes N-glycan chains and introduces negative charges by converting asparagine to aspartic acid.
Purpose of the Study:
- To describe simple in vivo and in vitro assay methods for detecting PNGase activity.
- To highlight the importance of monitoring both deglycosylation and charge changes for accurate PNGase activity assessment.
Main Methods:
- Monitoring deglycosylation using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).
- Detecting the introduction of negative charges using isoelectric focusing.
- Implementing both in vivo and in vitro assay methodologies.
Main Results:
- PNGase activity can be accurately monitored by detecting deglycosylation and charge alterations.
- SDS-PAGE effectively detects N-glycan removal.
- Isoelectric focusing successfully identifies the introduction of negative charges into core proteins.
Conclusions:
- PNGase plays a significant role in glycoprotein quality control and proteasomal degradation.
- The described assay methods provide a reliable means to quantify PNGase activity.
- Understanding PNGase function is vital for cellular protein homeostasis.
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