Lewis blood group alpha-(1->3/4)-fucosyltransferase.
Lewis FT.
Lewis(Le) blood group gene-dependent alpha-(1->3/4)-L-fucosyltransferase.
Reaction catalysed
GDP-beta-L-fucose + beta-D-galactosyl-(1->3)-N-acetyl-D-glucosaminyl-R <=> GDP + beta-D-galactosyl-(1->3)-(alpha-L-fucosyl-(1->4))-N-acetyl-beta-D-glucosaminyl-R
Comment(s)
Product of the Lewis blood group gene.
Normally acts on a glycoconjugate where R (see CA line) is a glycoprotein or glycolipid.
Although it is a 4-fucosyltransferase, it has a persistent 3-fucosyltransferase activity toward the glucose residue in free lactose.
Fucosylates on O-4 of an N-acetylglucosamine that carries a galactosyl group on O-3, unlike EC 2.4.1.152 which fucosylates on O-3 of an N-acetylglucosamine that carries a galactosyl group on O-4.
Enzymes catalyzing the 4-alpha-fucosylation of the GlcNAc in beta-D- Gal-(1->3)-beta-GlcNAc sequences (with some activity also as 3-alpha- fucosyltransferases) are present in plants, where the function in vivo is the modification of N-glycans.
In addition, the fucTa gene of Helicobacter strain UA948 encodes a fucosyltransferase with both 3-alpha- and 4-alpha-fucosyltransferase activities.