Which of the following enzymes is responsible for converting H antigen to A antigen?
Epitope conversion H to A illustrates exquisite donor acceptor specificity retaining glycosyltransferases Golgi apparatus. H antigen acceptor Gal beta1-4(Fuc alpha1-2)GlcNAc presents free three hydroxyl galactose for extension. A transferase GTA encoded chromosome nine q34 binds UDP GalNAc donor coordinated DxD motif manganese induced fit where Leu two sixty six Met and Gly two sixty eight Ala differentiate GalNAc versus galactose specificity compared B enzyme GTB. Catalysis forms alpha one three linkage adding GalNAc completing A antigen GalNAc alpha1-3(Fuc alpha1-2)Gal responsible ABO type A
Ref: Letts et al., J Biol Chem 2006, Crystal structure ABO transferases GalNAc transferase mechanism H to A.
