alpha 1,3-fucosyltransferase 9 (FUT9; Fuc-TIX) preferentially fucosylates the distal GlcNAc residue of polylactosamine chain while the other four alpha 1,3FUT members preferentially fucosylate the inner GlcNAc residue

We analyzed the substrate specificity of six human alpha 1,3-fucosyltransfe rases (alpha 1,3FUTs) for the 2-aminobenzamide (2AB)-labelled polylactosami ne acceptor, Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4GlcNAc-2AB (3LN-2AB), FUT9 preferentially fucosylated the distal GlcNAc residue of the polylactosamine chain while the other four alpha 1,3FUT mem bers, FUT3, FUT4, FUT5 and FUT6, preferentially fucosylated the inner GlcNA c residue. This indicated that FUT9 exhibits more efficient activity for th e synthesis of Lewis x carbohydrate epitope (Le(x); CD15; stage-specific em bryonal antigen-1 (SSEA-1)), In contrast, the other four members synthesize more effectively the internal Le(x) epitope, FUT7 could not transfer a fuc ose to an acceptor which is non-sialylated, (C) 1999 Federation of European Biochemical Societies.