FUT3

This gene encodes α1,3-fucosyltransferase 3 (FUT3). Six α1,3-fucosyltransferases (α3FUT): FUT3, FUT4, FUT5, FUT6, FUT7, and FUT9 are known and confirmed that each has specific substrate specificity in vitro. Except FUT7, these have activity to transfer fucose to GlcNAc of the type-2 lactosamine structure (Galβ1-4GlcNAcβ1-3-R) with α1-3-linkage. FUT3 has not only α1,3-fucosyltransferase activity but also α1,4-fucosyltransferase activity (i.e., activity toward type 1 lactosamine structure, Galβ1-3GlcNAcβ1-3-R), and it is proved in polymophism analysis that FUT3 is indispensable for synthesis of Lewis blood group antigen. In addition, FUT3 has activity to transfer fucose to GlcNAc of sialylated lactosamine structure (NeuAcα2-3Galβ1-3GlcNAcβ1-3-R or NeuAcα2-3Galβ1-4GlcNAcβ1-3-R) with α1-3-linkage; therefore, it is related to sialyl Lewis antigen. Sialyl Lewis a (sLea) antigen is synthesized by FUT3 only. FUT3 is known to be involved in synthesis of many Lewis blood group carbohydrate antigens (Lea, Leb, sLea, Lex, Ley, sLex). FUT3 is known with many polymorphism, some of which have no activity.