α3/4-Fucosyltransferases (α3/4-FUTs) are glycosyltransferases (GTs)
that catalyze the transfer of fucose in an α3/4-linkage onto the
N-acetylglucosamine residue from acceptors containing the type II or type I
(Galβ4/3GlcNAc, respectively) structures, thus synthesizing the fucosylated
Lewis (Le) carbohydrate determinants. Fucosyltransferase IX (FUT9), the most
recently identified member of the family, presents the higher divergence from the
other FUTs and its sequence is the only highly conserved among species. FUT9
synthesizes the Lewisx (Lex) epitope (Galβ4(Fucα3)GlcNAc). Recent evidence
has suggested that it is the enzyme responsible for the synthesis of Lex in the
mouse brain. Lex expression has been described in glycoproteins, proteoglycans
and glycolipids from the central nervous system (CNS) of diverse species,
including rodents and humans
