GALNT4

HO-Ser/Thr (Glycopeptide)		GalNAc(alpha1-O)-Ser/Thr (Glycopeptide)

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. GALNT4 is the fourth member of this enzyme family. This exhibits strong activities toward GalNAc-glycosylated peptide produced by GALNT2.

O-glycan Tn-antigen mucin tumor marker

Glc	Man	Gal	GlcNAc	GalNAc	Fuc	Xyl	Neu5Ac	Neu5Gc	GlcA	IdoA	GlcN