Figure 3.

Structural variations of the sialyl Tn (STn) antigen. An antibody targeting the sialyl Tn (STn) antigen may target one of many structurally similar glycans. For example, the nitrogen on the sialic acid residue can be modified with an acetyl group (Ac) or a glycolyl group (Gc). Additionally, O-acetylated variations can occur at numerous hydroxyl positions. The GalNAc residue can be attached to either serine or threonine. Finally, there may be a single STn residue on a peptide chain or there maybe additional STn residues in close proximity on the peptide chain (clustered STn). All of these structures could be described generally as STn.