Related Experiment Video
Updated: Jul 10, 2026

Targeting Cysteine Thiols for in Vitro Site-specific Glycosylation of Recombinant Proteins
Published on: October 4, 2017
N-linked glycosylation of folded proteins by the bacterial oligosaccharyltransferase
Michael Kowarik1, Shin Numao, Mario F Feldman
1Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule (ETH) Zurich, 8093 Zurich, Switzerland.
Abstract:
N-linked protein glycosylation is found in all domains of life. In eukaryotes, it is the most abundant protein modification of secretory and membrane proteins, and the process is coupled to protein translocation and folding. We found that in bacteria, N-glycosylation can occur independently of the protein translocation machinery. In an in vitro assay, bacterial oligosaccharyltransferase glycosylated a folded endogenous substrate protein with high efficiency and folded bovine ribonuclease A with low efficiency. Unfolding the eukaryotic substrate greatly increased glycosylation. We propose that in the bacterial system, glycosylation sites are located in flexible parts of folded proteins, whereas the eukaryotic cotranslational glycosylation evolved to a mechanism presenting the substrate in a flexible form before folding.
Related Concept Videos
Protein and Protein Structure
A protein's shape is critical to its function. For example, an enzyme can...
Protein Glycosylation
Glycosylation occurs in...
Oligosaccharide Assembly
Multiple sugar molecules that may or may...
Protein Modifications in the RER
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal sequences.
Protein Folding Quality Check in the RER
Production of Pharmaceuticals

