FUT9
Domain
The donor-binding domain adopts a Rossman-like fold involved in GDP-beta-L-fucose sugar donor interactions.
The acceptor-binding domain adopts a Rossman-like fold consisting of six-stranded parallel beta sheets characteristic of the Toll/interleukin-1 receptor (TIR) fold family. Interacts with the LacNAc unit of type 2 LacNAc and H-type 2 LacNAc structures. It contains the catalytic base Glu-137 which deprotonates the hydroxyl group of GlcNAc while forming bridging interactions with the donor sugar to position the catalytic machinery in the active site.
Function
Catalyzes alpha(1->3) linkage of fucosyl moiety transferred from GDP-beta-L-fucose to N-acetyl glucosamine (GlcNAc) within type 2 lactosamine (LacNAc, beta-D-Gal-(1->4)-beta-D-GlcNAc-) glycan attached to glycolipids and N- or O-linked glycoproteins. Fucosylates distal type 2 LacNAc and its fucosylated (H-type 2 LacNAc) and sialylated (sialyl-type 2 LacNAc) derivatives to form Lewis x (Lex) (CD15) and Lewis y (Ley) antigenic epitopes involved in cell adhesion and differentiation (PubMed:10386598, PubMed:10622713, PubMed:11278338, PubMed:12107078, PubMed:16282604, PubMed:17335083, PubMed:18395013, PubMed:23192350, PubMed:23263199, PubMed:29593094, PubMed:37202521). Generates Lex epitopes in the brain, presumably playing a role in the maintenance of neuronal stemness and neurite outgrowth in progenitor neural cells (By similarity) (PubMed:17335083, PubMed:23000574). Fucosylates the internal type 2 LacNAc unit of the polylactosamine chain to form VIM-2 antigen that serves as recognition epitope for SELE (PubMed:23192350). Can also modify milk oligosaccharides, in particular type 2 tetrasaccharide LNnT (PubMed:37202521).
Pathway
Protein modification; protein glycosylation.
Glycolipid biosynthesis.
Post-translational modifications
N-glycosylated with complex-type N-glycans. The glycan alpha-D-Man-(1->3)-beta-D-Man-(1->4)-GlcNAc-(1->4)-GlcNAc is attached at Asn-153.
Sequence Similarities
Belongs to the glycosyltransferase 10 family.
Tissue Specificity
Strongly expressed in forebrain and stomach, lower expression in spleen and peripheral blood leukocytes, and no expression in small intestine, colon, liver, lung, kidney, adrenal cortex or uterus (PubMed:10386598). Highly expressed in granulocytes. Not expressed in monocytes (PubMed:11278338).
Cellular localization
- Golgi apparatus
- trans-Golgi network membrane
- Single-pass type II membrane protein
- Golgi apparatus membrane
Alternative names
4-galactosyl-N-acetylglucosaminide 3-alpha-L-fucosyltransferase 9, Fucosyltransferase 9, Fucosyltransferase IX, Galactoside 3-L-fucosyltransferase, Fuc-TIX, FucT-IX, FUT9