Appendix 07. The Biosynthetic pathways of the A and B antigens


In 1959, Watkins and Morgan, and separately Ceppellini, proposed a hypothesis regarding the biosynthetic pathways of A and B antigens.  In this hypothesis, they postulated that the two glycosyltransferases (A and B transferases) encoded by the functional alleles (A and B alleles) catalyze the last step of biosynthesis. It was assumed that A transferase transfers a GalNAc residue to the acceptor H structure by alpha 1,3 glycosidic linkage, whereas B transferase transfers a galactose residue in place of a GalNAc.