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Background: Glycosylation is an enzyme-catalyzed post-translational modification that is distinct from glycation and is present on a majority of plasma proteins. N-glycosylation occurs on asparagine residues predominantly within canonical N-glycosylation motifs (Asn-X-Ser/Thr) although non-canonical N-glycosylation motifs Asn-X-Cys/Val have also been reported. Albumin is the most abundant protein in plasma whose glycation is well-studied in diabetes mellitus. However, albumin has long been considered a non-glycosylated protein due to absence of canonical motifs. Albumin contains two non-canonical N-glycosylation motifs, of which one was recently reported to be glycosylated.
Methods: We enriched abundant serum proteins to investigate their N-linked glycosylation followed by trypsin digestion and glycopeptide enrichment by size-exclusion or mixed-mode anion-exchange chromatography. Glycosylation at canonical as well as non-canonical sites was evaluated by liquid chromatography-tandem mass spectrometry (LC-MS/MS) of enriched glycopeptides. Deglycosylation analysis was performed to confirm N-linked glycosylation at non-canonical sites. Albumin-derived glycopeptides were fragmented by MS3 to confirm attached glycans. Parallel reaction monitoring was carried out on twenty additional samples to validate these findings. Bovine and rabbit albumin-derived glycopeptides were similarly analyzed by LC-MS/MS.
Results: Human albumin is N-glycosylated at two non-canonical sites, Asn and Asn. N-glycopeptides were detected at both sites bearing four complex sialylated glycans and validated by MS3-based fragmentation and deglycosylation studies. Targeted mass spectrometry confirmed glycosylation in twenty additional donor samples. Finally, the highly conserved Asn in bovine and rabbit serum albumin was also found to be glycosylated.
Conclusions: Albumin is a glycoprotein with conserved N-linked glycosylation sites that could have potential clinical applications.
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http://dx.doi.org/10.1186/s12967-024-05000-5 | DOI Listing |
Mol Genet Metab
August 2025
Laboratory for Molecular Diagnosis, Department of Human Genetics, KU Leuven, Leuven, Belgium. Electronic address:
The polyisoprenoid lipid dolichol is critical for eukaryotic glycosylation. It is used as the membrane anchor for mono- or oligosaccharides transferred during N-glycosylation, O/C-mannosylation and glycosylphosphatidylinositol anchor biosynthesis. Disorders affecting the synthesis or utilization of dolichol cause defective glycosylation and are therefore classified as Congenital Disorders of Glycosylation (CDG).
View Article and Find Full Text PDFDevelopmental delay and seizures with or without movement abnormalities (OMIM 617836) caused by heterozygous pathogenic variants in the gene (DHDDS-CDG) is a rare genetic disease that belongs to the progressive encephalopathy spectrum. It results in developmental delay in affected children, accompanied by myoclonus, seizures, ataxia and tremor, which worsens over time. encodes a subunit of a DHDDS/NUS1 cis-prenyltransferase ( PTase), a branch point enzyme of the mevalonate pathway essential for N-linked glycosylation.
View Article and Find Full Text PDFVet Res
August 2025
Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.
Porcine epidemic diarrhea virus (PEDV), a highly virulent enteric coronavirus, induces severe watery diarrhea and mortality in suckling piglets. The spike (S) protein, a critical mediator of viral entry, undergoes extensive N-linked glycosylation. To elucidate the functional significance of these post-translational modifications, we employed a reverse genetics system to generate 19 recombinant PEDV strains with single-site mutations at predicted N-glycosylation sites.
View Article and Find Full Text PDFArch Iran Med
July 2025
Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.
Background: PMM2-CDG, also known as congenital disorder of glycosylation type 1a, is the most common N-linked glycosylation disorder, characterized by a wide range of neurological and multisystem manifestations. Understanding the genotype-phenotype correlations is essential for accurate diagnosis and patient management. This study aims to identify the genetic cause of PMM2-CDG in an Iranian family with multiple affected members, and to analyze the genetic and clinical spectrum of the disorder through a comprehensive literature review.
View Article and Find Full Text PDFJ Biol Chem
August 2025
Institute of Plant Biotechnology and Cell Biology, Department of Biotechnology and Food Sciences, BOKU University; Vienna, Austria. Electronic address:
N-glycosylation is essential for protein folding in the endoplasmic reticulum (ER). Glycan attachment facilitates the binding of newly synthesised polypeptides to calnexin and calreticulin, two ER-resident lectins that act as chaperones and promote folding. The regulatory mechanism underlying this process is dictated by the glycan composition, and this study has elucidated the function of mannose trimming in the release of misfolded glycoprotein from ER quality control and subsequent transfer to ER-associated degradation (ERAD) in plants.
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