O-Linked N-Acetylglucosamine

Many cellular proteins, including nuclear pore, oncogene, cytoskeletal, heat shock, viral and transcription regulatory proteins contain single O-linked N-acetylglucosamine (O-GlcNAc) residues attached to serine or threonine residues. It has been observed that O-GlcNAc glycosylated proteins tend to be under phosphorylated relative to unglycosylated proteins and that O-GlcNAc bearing proteins tend to be found in multimeric complexes. This has led to the suggestion that O-GlcNAc glycosylation may obscure phosphorylation sites and acts as a signaling mechanism or mediator of signaling.