Histo-blood group ABO system transferase (ABO)

This protein is based on the ABO blood group system. The histo-blood group ABO involves three carbohydrate antigens: A, B, and H.

A, B, and AB individuals express a glycosyltransferase activity that converts the H antigen to the A antigen (by addition of UDP-GalNAc) or to the B antigen (by addition of UDP-Gal), whereas O individuals lack such activity. .