This enzyme catalyzes the GalNAc-transfer from UDP-GalNAc to Ser or Thr residue in the protein. The product is GalNAc-alpha-O-Ser/Thr structure, so-called Tn-antigen, which is the base structure of mucin type O-glycan. The acceptor substrate (protein) is typically Mucin. GALNT16 is the 16th member of this enzyme family. This isozyme is identified by Raman et al. in 2012.
This page does not indicate all of the enzymatic reaction, and expression of "GALNT16".