2.4.1.144 UDP-N-acetyl-alpha-D-glucosamine + beta-D-GlcNAc-(1->2)-alpha-D-Man-(1->3)-[beta-D-GlcNAc-(1->2)-alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-beta-D-GlcNAc-N-Asn-[protein] = UDP + beta-D-GlcNAc-(1->2)-alpha-D-Man-(1->3)-[beta-D-GlcNAc-(1->2)-alpha-D-Man-(1->6)]-[beta-D-GlcNAc-(1->4)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-beta-D-GlcNAc-N-Asn-[protein] R represents the remainder of the N-linked oligosaccharide in the glycoprotein acceptor. The action of this enzyme probably prevents further attachment of N-acetylglucosamine residues to the growing carbohydrate chain. - 2.4.1.144 UDP-N-acetyl-alpha-D-glucosamine + beta-D-GlcNAc-(1->2)-alpha-D-Man-(1->3)-[beta-D-GlcNAc-(1->2)-alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-beta-D-GlcNAc-N-Asn-[protein] = UDP + beta-D-GlcNAc-(1->2)-alpha-D-Man-(1->3)-[beta-D-GlcNAc-(1->2)-alpha-D-Man-(1->6)]-[beta-D-GlcNAc-(1->4)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-beta-D-GlcNAc-N-Asn-[protein] sequential, random or partially random mechanism 638228