Related Experiment Video
Updated: Jun 13, 2026

Analysis of SCAP N-glycosylation and Trafficking in Human Cells
Published on: November 8, 2016
Cosmc is an essential chaperone for correct protein O-glycosylation
Yingchun Wang1, Tongzhong Ju, Xiaokun Ding
1Departments of Biochemistry and Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA.
Abstract:
Cosmc is a molecular chaperone thought to be required for expression of active T-synthase, the only enzyme that galactosylates the Tn antigen (GalNAcalpha1-Ser/Thr-R) to form core 1 Galbeta1-3GalNAcalpha1-Ser/Thr (T antigen) during mucin type O-glycan biosynthesis. Here we show that ablation of the X-linked Cosmc gene in mice causes embryonic lethality and Tn antigen expression. Loss of Cosmc is associated with loss of T-synthase but not other enzymes required for glycoprotein biosynthesis, demonstrating that Cosmc is specific in vivo for the T-synthase. We generated genetically mosaic mice with a targeted Cosmc deletion and survivors exhibited abnormalities correlated with Tn antigen expression that are related to several human diseases.
Related Concept Videos
Protein Glycosylation
Glycosylation occurs in...
Oligosaccharide Assembly
Multiple sugar molecules that may or may...
Protein Folding Quality Check in the RER
Molecular Chaperones and Protein Folding
The...
Molecular Chaperones and Protein Folding
The...
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.

