Galactose-3-O-Sulfotransferase 4 (GAL3ST4)

GAL3ST4 encodes a member of the galactose-3-O-sulfotransferase protein family. The product of this gene catalyzes sulfonation by transferring a sulfate to the C-3' position of galactose residues in O-linked glycoproteins. This enzyme is highly specific for core 1 structures, with asialofetuin, Gal-beta-1,3-GalNAc and Gal-beta-1,3 (GlcNAc-beta-1,6)GalNAc being good substrates.The deduced 486-amino acid protein has a calculated molecular mass of about 54 kD. GAL3ST4 contains an N-terminal hydrophobic segment, which indicates that it has a type II transmembrane topology, 2 conserved regions that contain putative adenosine 3-prime-phosphate 5-prime-phosphosulfate (PAPS)-binding motifs, and a single N-glycosylation site. It shares 33%, 39%, and 30% amino acid identity with GAL3ST1, GAL3ST2, and GAL3ST3, respectively.