The alpha-1,3-fucosyltransferases constitute a large family of glycosyltransferases with a high degree of homology. The enzymes of this family comprise 3 main activity patterns called myeloid, plasma, and Lewis, based on their capacity to transfer alpha-L-fucose to distinct oligosaccharide acceptors, their sensitivity to N-ethylmaleimide inhibition, their cation requirements, and their tissue-specific expression patterns. The different categories of alpha-1,3-fucosyltransferases are sequentially expressed during embryo-fetal development. Transfection of FUT6 cDNA into mammalian cells conferred alpha-1,3-fucosyltransferase activity to the cells, resulting in cell surface expression of Lewis x and sialyl-Lewis x carbohydrates. Antibodies raised against another epitope of FUT6 localized the enzyme to Weibel-Palade bodies, endothelial storage granules.