In enzymology, a protein N-acetylglucosaminyltransferase (EC 2.4.1.94) is an enzyme that catalyzes the chemical reaction

UDP-N-acetyl-D-glucosamine + protein ${\displaystyle \rightleftharpoons }$ UDP + 4-N-(N-acetyl-D-glucosaminyl)-protein

Thus, the two substrates of this enzyme are UDP-N-acetyl-D-glucosamine and protein, whereas its two products are UDP and 4-N-(N-acetyl-D-glucosaminyl)-protein.

This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is UDP-N-acetyl-D-glucosamine:protein beta-N-acetyl-D-glucosaminyl-transferase. Other names in common use include uridine diphosphoacetylglucosamine-protein, acetylglucosaminyltransferase, uridine diphospho-N-acetylglucosamine:polypeptide, beta-N-acetylglucosaminyltransferase, and O-GlcNAc transferase.

• Khalkhall Z, Marshall RD (1975). "Glycosylation of ribonuclease A catalysed by rabbit liver extracts". Biochem. J. 146 (2): 299–307. PMC 1165306. PMID 1156375.
• Khalkhali Z, Marshall RD (1976). "UDP-N-acetyl-D-glucosamine-asparagine sequon N-acetyl-beta-D-glucosaminyl-transferase-activity in human serum". Carbohydr. Res. 49: 455–73. doi:10.1016/S0008-6215(00)83163-8. PMID 986874.
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• N-Acetylglucosaminyltransferases at the U.S. National Library of Medicine Medical Subject Headings (MeSH)