Three putative α1→3/4-fucosyltransferase (α1→3/4-FucT) genes have been detected in the Arabidopsis thaliana genome. The products of two of these genes have been identified in vivo as core α1→3-FucTs involved in N-glycosylation. An orthologue of the third gene was isolated from a Beta vulgaris cDNA library. The encoded enzyme efficiently fucosylates Galβ1→3GlcNAcβ1→3Galβ1→4Glc. Analysis of the product by 400 MHz 1H-nuclear magnetic resonance spectroscopy showed that the product is α1→4-fucosylated at the N-acetylglucosamine residue. In vitro, the recombinant B. vulgaris α1→4-FucT acts efficiently only on neutral type 1 chain-based glycan structures. In plants the enzyme is expected to be involved in Lewisa formation on N-linked glycans.
