Non-protein ubiquitin clipping (NoPro-clipping) method identifies ubiquitinated glycogen and metabolites in cells and tissues (nature.com)

• NoPro-clipping enables detection of ubiquitination on non-protein biomolecules using mass spectrometry.
• Ubiquitinated glycogen is found in mouse liver, muscle, brain, and human muscle; increases during fasting, indicating role in glycogen catabolism.
• Method also identifies ubiquitinated glycerol and spermine, expanding ubiquitin's substrate scope beyond proteins.

"Researchers developed NoPro-clipping, a mass spectrometry technique combining ubiquitin clippases and sortase labeling to detect ubiquitination on non-protein biomolecules. Using this method, they identified ubiquitinated glycogen in mouse tissues and human cells, with highest abundance in liver and skeletal muscle. During fasting, liver glycogen ubiquitination increased eightfold, suggesting a role in glycogen catabolism. Ubiquitinated glycerol and spermine were also detected, expanding ubiquitin's role beyond protein modification."