Extracellular O -linked β-N -acetylglucosamine: Its biology and relationship to human disease MINIREVIEWS

The O -linked β-N -acetylglucosamine (O -GlcNAc)ylation of cytoplasmic and nuclear proteins regulates basic cellular functions and is involved in the etiology of neurodegeneration and diabetes. Intracellular O-GlcNAcylation is catalyzed by a single O-GlcNAc transferase, O-GlcNAc transferase (OGT). Recently, an atypical O-GlcNAc transferase, extracellular O -linked β-N -acetylglucosamine (EOGT), which is responsible for the modification of extracellular O -GlcNAc, was identified. Although both OGT and EOGT are regulated through the common hexosamine biosynthesis pathway, EOGT localizes to the lumen of the endoplasmic reticulum and transfers GlcNAc to epidermal growth factor-like domains in an OGT-independent manner. In Drosophila , loss of Eogt gives phenotypes similar to those caused by defects in the apical extracellular matrix. Dumpy, a membrane-anchored apical extracellular matrix protein, was identified