Description
N-glycans, O-glycans and glycolipids are frequently fucosylated at terminal sites. Therefore, fucose is often part of a sugar epitope with important biological function. Well-known fucose-containing glycans include Lewis and ABO blood group antigens. Lewis epitopes are key elements involved in the leukocyte homing and extravasation process and thus are important for lymphocyte maturation and natural defense functions. Fucose-containing glycans also play critical roles in cell signaling and development. More than 10 fucosyltransferases have been cloned. FUT1 and FUT2 are alpha 1-2 fucosyltransferases and are responsible for ABO blood-group antigen synthesis. FUT8 is an alpha 1-6 fucosyltransferase that adds a fucose to the chitobiose core of N-glycans. FUT3, FUT4, FUT5, FUT6, FUT7 and FUT9 are alpha 1-3 or alpha 1-4 fucosyltransferases and are responsible for Lewis antigen generation. In particular, FUT9 synthesizes the Lewis X oligosaccharide (CD15) in the organ buds progressing in mesenchyma during embryogenesis and in mature granulocytes. The activity of this enzyme has been measured with a phosphatase-coupled method