InterPro domain: IPR004139

The biosynthesis of disaccharides, oligosaccharides and polysaccharides involves the action of hundreds of different glycosyltransferases. These enzymes catalyse the transfer of sugar moieties from activated donor molecules to specific acceptor molecules, forming glycosidic bonds. A classification of glycosyltransferases using nucleotide diphospho-sugar, nucleotide monophospho-sugar and sugar phosphates ([intenz:2.4.1.-]) and related proteins into distinct sequence based families has been described [ 1 ]. This classification is available on the CAZy (CArbohydrate-Active EnZymes) web site. The same three-dimensional fold is expected to occur within each of the families. Because 3-D structures are better conserved than sequences, several of the families defined on the basis of sequence similarities may have similar 3-D structures and therefore form 'clans'.

Alpha-1,3-mannosyl-glycoprotein beta-1,2-N-acetylglucosaminyltransferase (GNT-I, GLCNAC-T I) 2.4.1.101 transfers N-acetyl-D-glucosamine from UDP to high-mannose glycoprotein N-oligosaccharide. This is an essential step in the synthesis of complex or hybrid-type N-linked oligosaccharides. The enzyme is an integral membrane protein localized to the Golgi apparatus, and is probably distributed in all tissues [ 2 ]. Protein O-linked-mannose beta-1,2-N-acetylglucosaminyltransferase 1 (POMGNTI, GNT-I.2) participates in O-mannosyl glycosylation by catalyzing the addition of N-acetylglucosamine to O-linked mannose on glycoproteins [ 3 , 4 , 5 ]. These proteins are members of the glycosyl transferase family 13 ( GH13 )

1. A classification of nucleotide-diphospho-sugar glycosyltransferases based on amino acid sequence similarities. Biochem. J. 326 ( Pt 3), 929-39
2. Molecular cloning and characterization of cDNA coding for beta1, 2N-acetylglucosaminyltransferase I (GlcNAc-TI) from Nicotiana tabacum. Glycobiology 9, 779-85
3. Muscular dystrophy and neuronal migration disorder caused by mutations in a glycosyltransferase, POMGnT1. Dev. Cell 1, 717-24
4. Carbohydrate-binding domain of the POMGnT1 stem region modulates O-mannosylation sites of α-dystroglycan. Proc. Natl. Acad. Sci. U.S.A. 113, 9280-5
5. Mammalian O-mannosylation of cadherins and plexins is independent of protein O-mannosyltransferases 1 and 2. J. Biol. Chem. 292, 11586-11598