Fig. 2.

Processing of tumor cell membranes to express α-gal epitopes on asparagine-linked (N-linked) carbohydrate chains of glycoproteins. Synthesis of α-gal epitopes is achieved in a suspension containing neuraminidase and recombinant α-1,3-galactosyltransferase (rα1,3GT) in a two-step reaction: (1) removal of sialic acid (SA) from carbohydrate chains by neuraminidase to expose the penultimate N-acteyllactosamine residues (Galβ1-4GlcNAc-R), and (2) linking of galactose from the sugar donor uridine-diphosphate-galactose (UDP-Gal) to the exposed N-acetyllactosamine residues by rα1,3GT to form α-gal epitopes. The de novo synthesized α-gal epitopes readily bind the natural anti-Gal Ab