EOGT, also known as EGF domain-specific O-linked N-acetylglucosamine transferase, is involved in the regulation of Notch receptor. O-GlcNAc (O-linked b-N-acetylglucosamine) is introduced by a single intracellular O-GlcNAc transferase (OGT) and a single extracellular O-GlcNAc transferase (EOGT). O-GlcNAc results from the addition of a single N-acetylglucosamine residue to serine/threonine residues. Recombinant mouse EOGT, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.