Potential glycopeptide transferase involved in O-linked oligosaccharide biosynthesis (By similarity). In contrast to other members of the family, it does not act as a peptide transferase that transfers GalNAc onto serine or threonine residue on peptides that have been tested. Some peptide transferase activity is however not excluded, considering that its appropriate peptide substrate may remain unidentified. Protein modification; protein glycosylation. There are two conserved domains in the glycosyltransferase region: the N-terminal domain (domain A, also called GT1 motif), which is probably involved in manganese coordination and substrate binding and the C-terminal domain (domain B, also called Gal/GalNAc-T motif), which is probably involved in catalytic reaction and UDP-Gal binding. Belongs to the glycosyltransferase 2 family. GalNAc-T subfamily. In contrast to other members of the family, it lacks the C-terminal ricin B-type lectin domain, which usually contributes to the glycopeptide specificity. It instead contains a motif that may retain its secretion form the endoplasmic reticulum.