Alpha-1,3-mannosyl-glycoprotein 4-beta-N-acetylglucosaminyltransferase (, N-acetylglucosaminyltransferase IV, N-glycosyl-oligosaccharide-glycoprotein N-acetylglucosaminyltransferase IV, beta-acetylglucosaminyltransferase IV, uridine diphosphoacetylglucosamine-glycopeptide beta4-acetylglucosaminyltransferase IV, alpha-1,3-mannosylglycoprotein beta-1,4-N-acetylglucosaminyltransferase, GnTIV) is an enzyme with systematic name UDP-N-acetyl-D-glucosamine:3-(2-(N-acetyl-beta-D-glucosaminyl)-alpha-D-mannosyl)-glycoprotein 4-beta-N-acetyl-D-glucosaminyltransferase. This enzyme catalyses the following chemical reaction
R represents the remainder of the N-linked oligosaccharide in the glycoprotein acceptor.