Oglucosylation

O-glucosylation is a post-translational modification in which a glucose molecule is attached by an O-glycosidic bond to the hydroxyl group of specific amino acids in proteins. In animals and other metazoans, it most commonly targets serine residues within epidermal growth factor-like (EGF) repeats, whereas in plants many hydroxyproline residues in cell wall glycoproteins are glucosylated. The glucose donor is typically UDP-glucose.

In animals, a key example involves the modification of Notch receptors. A family of protein O-glucosyltransferases, including POGLUT1, transfers glucose from UDP-glucose to serine residues in EGF repeats. This O-glucose modification can influence folding, stability, trafficking, and signaling of Notch receptors; defects can disrupt development in model organisms and are a focus of developmental biology research.

In plants, hydroxyproline O-glucosylation initiates the O-glycosylation of extensins and related cell wall glycoproteins. Hyp residues are formed by prolyl hydroxylases; Hyp-O-glucosyltransferases add glucose, which is often extended by other glycosyltransferases to form longer chains containing galactose and arabinose. These glycans contribute to cell wall integrity, protein stability, and interactions with the cell wall matrix.

Detection and study employ glycoproteomics methods, including mass spectrometry, and functional analyses use gene knockouts or enzymatic assays. O-glucosylation thus represents a conserved strategy for modulating protein function across kingdoms, with context- and residue-specific roles.