What functions and relevance is the next important question. Was it just a spilled-over? What selectivity and specificity?

Reversible Tyr-O-GlcNAcylation

Ma's Lab found O-GlcNAc on over 120 Tyr residues on proteins by an integrated ultradeep O-GlcNAc proteomics workflow. OGT and OGA can do Tyr in vitro. 👍

Wow, how could we have missed that >40 years after the discovery of O-GlcNAc? 😅

www.pnas.org/doi/10.1073/...

Seems great. What's the link to the tool you mentioned?

Distinct O-Acetylation Patterns of Serum Glycoproteins among Humans, Mice, and Rats O-Acetylation is a significant chemical modification of sialic acids on glycoproteins with diverse biological functions. As two important animal models, mice and rats have been widely used for various...

Intriguing differences, if further verified ...

All sialoglycopeptides (sGP) in human sera carry Neu5Ac without any O-acetylation; 90% of sGP in rat sera carry Neu5Ac, with > 60% further O-acetylated. 99% of sGP in mouse sera carry Neu5Gc including 12% O-acetylated.
pubs.acs.org/doi/10.1021/...