Polypeptide N-acetylgalactosaminyltransferase 13 (GALNT13)

Catalyzes the initial reaction in O-linked oligosaccharide biosynthesis, the transfer of an N-acetyl-D- galactosamine residue to a serine or threonine residue on the protein receptor. Has a much stronger activity than GALNT1 to move GalNAc into mucin peptides, such as Muc5Ac and Muc7.

Willing to glycosylate SDC3. May be responsible for the synthesis of Tn antigen in neuronal cells.