O-linked beta-N-acetylglucosamine (O-GlcNAc) is a sugar attachment to serine or threonine hydroxyl moieties on nuclear and cytoplasmic proteins. O-GlcNAc modified proteins are generally either cytoplasmic or nuclear proteins, and unlike asparagine-linked or mucin-type O-glycosylation, O-GlcNAc is not further processed into a complex oligosaccharide.
