InterPro domain: IPR026116

The glycosyltransferase family 18 consists of alpha-1,6-mannosylglycoprotein 6-beta-N-acetylglucosaminyltransferases. This enzyme catalyses the addition of N-acetylglucosamine in beta 1-6 linkage to the alpha-linked mannose of biantennary N-linked oligosaccharides. It is one of the most important enzymes involved in the regulation of the biosynthesis of glycoprotein oligosaccharides.

In humans, two homologues have been described, Gnt-V(A) and Gnt-VB (GnT-IX). Gnt-VB is predominantly expressed in brain and catalyses the transfer of N-acetylglucosamine (GlcNAc) to the beta 1-6 linkage of the mannose residue of GlcNAcbeta1,2-Manalpha on both the alpha1,3- and alpha1,6-linked mannose arms in the core structure of N-glycan. Gnt-VB could be responsible for the synthesis of a unique oligosaccharide structure in the brain. It plays an active role in modulating integrin and laminin-dependent adhesion and migration of neuronal cells via its activity in the O-mannosyl glycan pathway [ 1 , 2 , 3 , 4 , 5 ].

Caenorhabditis elegans has only one homologue [ 6 ].

1. A novel beta(1,6)-N-acetylglucosaminyltransferase V (GnT-VB)(1). FEBS Lett. 554, 515-9
2. Molecular cloning and characterization of human GnT-IX, a novel beta1,6-N-acetylglucosaminyltransferase that is specifically expressed in the brain. J. Biol. Chem. 278, 43102-9
3. N-Acetylglucosaminyltransferase IX acts on the GlcNAc beta 1,2-Man alpha 1-Ser/Thr moiety, forming a 2,6-branched structure in brain O-mannosyl glycan. J. Biol. Chem. 279, 2337-40
4. Integrin-dependent neuroblastoma cell adhesion and migration on laminin is regulated by expression levels of two enzymes in the O-mannosyl-linked glycosylation pathway, PomGnT1 and GnT-Vb. Exp. Cell Res. 312, 2837-50
5. N-acetylglucosaminyltranferase VB expression enhances beta1 integrin- dependent PC12 neurite outgrowth on laminin and collagen. J. Neurochem. 97, 947-56
6. The Caenorhabditis elegans gene, gly-2, can rescue the N-acetylglucosaminyltransferase V mutation of Lec4 cells. J. Biol. Chem. 277, 22829-38