A(ABO)

This enzyme is the enzyme that synthesizes A antigen, which is the blood group carbohydrate antigen, encoded by the ABO gene. Its enzyme activity is a1,3-N-acetylgalactosaminyltransferase activity that transfers GalNAc from the donor UDP-GalNAc to the galactose residue of the non-reducing terminal of the acceptor (H type carbohydrate antigen) by an a1-3 bond.
A blood type Histo-Blood group antigen a1,3-N-acetylgalactosaminyltransferase

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