fucosylated

Fucosylated refers to molecules that carry one or more fucose residues attached by glycosidic bonds. In biology, fucosylation is the enzymatic addition of fucose to proteins or lipids, most often on N- or O-linked glycans and glycosphingolipids. Fucosylated structures participate in diverse processes, including cell–cell adhesion, signaling, immune recognition, and host–pathogen interactions.

Enzymology and structure: Fucosyltransferases (FUTs) catalyze the transfer of fucose from GDP-fucose to specific acceptors. In humans, FUT family members include FUT1–FUT11. Core fucosylation of N-glycans is performed by FUT8. Antennary or terminal fucosylation by FUT3, FUT4, FUT5, FUT6, FUT7, and FUT9 creates Lewis-type antigens such as Le^a, Le^b, Le^x, and Le^y. Alpha-1,2 fucosylation by FUT1/2 generates H antigens on type 1 or type 2 chains and is linked to the ABO blood group system.

Biological importance: Fucosylated ligands for selectins enable leukocyte rolling along the vascular endothelium, a key step in immune cell trafficking. Fucosylated Lewis antigens modulate cell–cell interactions and receptor recognition. In humans, fucosylated oligosaccharides are abundant in milk as human milk oligosaccharides (HMOs), such as 2'-fucosyllactose, which influence gut microbiota and immune development.

Clinical relevance and applications: Altered fucosylation patterns are associated with cancer, inflammatory diseases, and congenital disorders of glycosylation. Defects in GDP-fucose transport can cause leukocyte adhesion deficiency type II, a severe immunodeficiency. In biotechnology and therapeutics, manipulating fucosylation can affect antibody effector functions; afucosylated antibodies often show enhanced antibody-dependent cellular cytotoxicity.