DISTINCT SUBSTRATE SPECIFICITIES OF 5 HUMAN ALPHA-1,3-FUCOSYL-TRANSFERASES FOR IN-VIVO SYNTHESIS OF THE SIALYL-LEWIS-X AND LEWIS-X EPITOPES

Five different human alpha-1,3-fucosyltransferase genes, the Fuc-TIII, Fuc-TIV, Fuc-TV, Fuc-TVI and Fuc-TVII genes, have been cloned to date . We transfected HeLa cells and Namalwa cells with each of the five di fferent genes, and established a series of stable cloned transformant cells. Thin-layer chromatography immunostaining analysis revealed that all five enzymes were able to synthesize sialyl Lewis x (sLe(x)) epit opes on glycolipids in HeLa cells, but each enzyme showed a different preference as to the carbohydrate chain length on glycolipids as accep tor substrates. Fuc-TIII and Fuc-TV showed very similar patterns of sL e(x) positive bands, which indicated that the enzymes have similar acc eptor substrate specificities. Fuc-TVI exhibited a little different pa ttern from those of the former two enzymes. Fuc-TIV and Fuc-TVII showe d similarity in the positive bands, however, their patterns were quite different from those of the former three enzymes. Four enzymes except for Fuc-TVII were able to synthesize the Lewis x (Le(x)) epitope on g lycolipids in HeLa cells. Fuc-TV alone showed a little different patte rn of Le(x) positive bands from those of the other three enzymes. Flow cytometric analysis of HeLa cells and Namalwa cells again demonstrate d the similar specificities of Fuc-TIII and Fuc-TV. They exhibited sim ilar stronger staining with FH6 (anti-sLe(x)) antibodies than that wit h the other enzymes. A phylogenetic tree of the five enzymes construct ed using the neighbor-joining method showed good agreement with the si milarities in the enzyme substrate specificity. (C) 1997 Academic Pres s.