Glycosyltransferase that participates in the transfer of N-acetylglucosamine (GlcNAc) to the core mannose residues of N- linked glycans. Catalyzes the formation of the GlcNAcbeta1-4 branch on the GlcNAcbeta1-2Manalpha1-3 arm of the core structure of N-linked glycans. Essential for the production of tri- and tetra-antennary N-linked sugar chains. Has lower affinities for donors or acceptors than MGAT4A, suggesting that, under physiological conditions, it is not the main contributor in N- glycan biosynthesis.
Alpha-1,3-mannosyl-glycoprotein 4-beta-N-acetylglucosaminyltransferase B; alpha-1,3-mannosyl-glycoprotein beta-1,4-N-acetylglucosaminyltransferase; aminyltransferase; GlcNAc-T IVb; mannosyl (alpha-1,3-)-glycoprotein beta-1,4-N-acetylglucosaminyltransferase, isoenzyme B; N-acetylglucosaminyltransferase IVb; N-glycosyl-oligosaccharide-glycoprotein N-acetylglucosaminyltransferase IVb; UDP-N-acetylglucosamine: alpha-1,3-D-mannoside beta-1,4-N-acetylglucosaminyltransferase IV; UDP-N-acetylglucosamine: alpha-1,3-D-mannoside beta-1,4-N-acetylglucosaminyltransferase IVb