2.4.1.143	evolution	compared with the structure of human GnTII, the amino acid residues involved in catalytic activity and substrate recognition are almost fully conserved in Bombyx mori GnTII, which is consistent with its enzymatic properties	759523	
2.4.1.143	evolution	enzyme TbGT15 belongs to the trypanosome beta3-glycosyltransferase superfamily	-, 759473	
2.4.1.143	evolution	MGAT2 has been characterized from mammalian, plant, and insect sources, enzyme structure comparisons, overview	760070	
2.4.1.143	malfunction	deletion of TbGT15 is accompanied by the absence of complex N-glycans, as well as alterations in the biosynthesis of the giant poly-Lac-dently from prior TbGnTI action, which is in contrast to canonical GnTIIs that only use substrates after modification by GnTI, i.e. Manalpha1-6(GlcNAcbeta1-2Manalpha1-3)Manbeta1-4GlcNAcbeta1-4GlcNAc	-, 759473	
2.4.1.143	malfunction	human deficiency in MGAT2 leads to carbohydrate-deficient glycoprotein syndrome type IIa (CDG IIa) characterized by facial dysmorphy, ventricular septal defects, and severely retarded psychomotor development. To date, five MGAT2 mutations have been identified in CDG IIa patients, all residing within the catalytic domain (H262R, S290F, N318D, C339ter, and K237N). Four of the mutations (H262R, S290F, N318D, C339ter) exhibit significantly reduced (compound heterozygote N318D:C339ter) or a complete absence of enzyme activity (H262R, S290F). Three of the residues are nonconserved (H262, N318, and K237), and N318 and K237 H-bond directly or indirectly with the UDP-GlcNAc donor. The S290 is a conserved residue that stabilizes the core of the GT-A fold through H-bonds to peptide bond backbone residues. The H262R, S290F, and K237N mutations break these critical hydrogen bonds and introduce steric clashes to destabilize the protein. The isosteric N318D mutation results in reduced activity similar to the 30 to 37fold reduction in kcat/Km for the N318A	760070	
2.4.1.143	metabolism	Asn-linked oligosaccharides are extensively modified during transit through the secretory pathway, first by trimming of the nascent glycan chains and subsequently by initiating and extending multiple oligosaccharide branches from the trimannosyl glycan core. Trimming and branching pathway steps are highly ordered and hierarchal based on the precise substrate specificities of the individual biosynthetic enzymes. A key committed step in the synthesis of complex-type glycans is catalyzed by N-acetylglucosaminyltransferase II (MGAT2), an enzyme that generates the second GlcNAcbeta1,2- branch from the trimannosyl glycan core using UDPGlcNAc as the sugar donor. Enzymatic steps required for the synthesis of the complex-type structures, processing of N-glycans from Man9GlcNAc2 to complex-type structures includes GlcNAc addition by MGAT1, Man trimming by MAN2A1, and GlcNAc addition by MGAT2, pathway overview	760070	
2.4.1.143	metabolism	beta-1,2-N-acetylglucosaminyltransferase II is a key enzyme for complex-type N-glycan biosynthesis. Both insect and mammalian cells produce Man(alpha1->6)[GlcNAc(beta1->2)Man(alpha1->3)]Man(beta1->4)GlcNAc(beta1->4)GlcNAc (MGn) glycan as an intermediate during N-glycan processing. In insect cells, beta-N-acetylglucosaminidase (fused lobes, FDL) removes a GlcNAc residue of the alpha1-3 arm of MGn glycan to produce Man(alpha1->6)[Man(alpha1->3)]ManGlcNAc2 (MM), a core structure from paucimannose-type N-glycans	759523	
2.4.1.143	metabolism	N-acetylglucosaminyltransferase I or II initiate the elaboration of the Manalpha1-3 and Manalpha1-6 arms, respectively, of the conserved trimannosyl-N-acetylchitobiosyl core of N-linked glycans. Proposed scheme for poly-LacNAc-containing N-glycans of bloodstream form trypanosomes, overview	-, 759473	
2.4.1.143	metabolism	part of N-glycan pathway	704576	
2.4.1.143	metabolism	the enzyme functions at the N-glycan processing branch point and is one of the major factors determining the net outcome of the insect cell N-glycosylation pathway	722801	
2.4.1.143	additional information	Rossmann-like fold that employs conserved divalent cation-dependent substrate interactions with the UDP-GlcNAc donor. MGAT2 interactions with the extended glycan acceptor are distinct from other related glycosyltransferases. These interactions are composed of a catalytic subsite that binds the Man-(alpha1,6)- monosaccharide acceptor and a distal exosite pocket that binds the GlcNAc-beta1,2Man-alpha1,3Manbeta- substrate recognition arm. Substrate binding by MGAT2 employs both conserved and convergent catalytic subsite modules to provide substrate selectivity and catalysis. More broadly, the MGAT2 active-site architecture demonstrates how glycosyltransferases create complementary modular templates for regiospecific extension of glycan structures in mammalian cells. The enzyme MGAT2 employs a UDP-GlcNAc donor in a Mn2+-dependent inverting catalytic mechanism. structural basis for substrate recognition by MGAT2, structure-function analysis, structure comparisons, catalytic mechanism, detailed overview	760070	
2.4.1.143	additional information	the enzyme sequence contains a DXD motif, which is generally involved in catalytic activity of known GTs	-, 759473	
2.4.1.143	physiological function	beta-1,2-N-acetylglucosaminyltransferase II (GnTII) catalyzes the transfer of GlcNAc from a UDP-GlcNAc donor to the alpha1-6 arm of MGn glycan to produce biantennary complex-type glycans in mammalian cells	759523	
2.4.1.143	physiological function	beta-1,2-N-acetylglucosaminyltransferase II (GnTII) is a Golgi-localized type II transmembrane enzyme that catalyzes the transfer of N-acetylglucosamine to the 6-arm of the trimanosyl core of N-glycans, an essential step in the conversion of oligomannose-type to complex-type N-glycans	759522	
2.4.1.143	physiological function	TbGT15 is the glycosyltransferase responsible for the transfer of beta1-2-linked GlcNAc to the alpha1-6-linked alpha-D-mannopyranosyl residue of Manalpha1-6(Manalpha1-3)Manbeta1-4GlcNAcbeta1-4GlcNAc. The enzyme initiates the elaboration of the Manalpha1-6 arms of the conserved trimannosyl-N-acetylchitobiosyl core of N-linked glycans, structure and biosynthesis of complex N-glycans in the human pathogen are analyzed, and the adaptation by trypanosomes of beta3-glycosyltransferase family members to catalyze beta-1-2 glycosidic linkages is demonstrated. TbGT15 is a non-essential gene in Trypanosoma brucei bloodstream form cells	-, 759473