Beta-1,4-N-Acetyl Galactosaminyl Transferase 3 (b4GALNT3)

B4GALNT3 transfers N-acetylgalactosamine (GalNAc) onto glucosyl residues to form N,N-prime-diacetyllactosediamine, a unique terminal structure of cell surface N-glycans. The deduced 999-amino acid protein has a typical type II topology, with an N-terminal transmembrane domain, 4 potential N-glycosylation sites, a DXH sequence though to participate in divalent cation binding, and a C-terminal WGGED motif characteristic of beta-4GTs.a soluble form of B4GalNAcT3 expressed in human embryonic kidney cells transferred GalNAc to N-acetylglucosyl (GlcNAc) beta-benzyl through a beta-1,4-linkage to form LDN. B4GalNAcT3 transferred GalNAc to all N- and O-glycans examined that contained GlcNAc at their nonreducing termini. Some glycohormones contain N,N-prime-LDN structures in their N-glycans.