FUT4

FUT4, or fucosyltransferase 4, is an enzyme encoded by the FUT4 gene in humans. It belongs to the fucosyltransferase family and resides in the Golgi apparatus, where it transfers fucose from GDP-fucose to specific glycan substrates. FUT4 predominantly catalyzes alpha1,3-fucosylation to generate the Lewis X antigen (CD15) on glycoproteins and glycolipids.

The Lewis X epitope formed by FUT4 serves as a carbohydrate recognition motif involved in cell–cell adhesion. By creating Lewis X–containing ligands, FUT4 participates in selectin-mediated adhesion, influencing leukocyte trafficking and inflammatory responses. The enzyme's activity can thus impact processes such as immune cell recruitment and vascular interactions.

Expression of FUT4 is observed in multiple tissues, with notable activity in leukocytes and endothelial cells. Its regulation is context-dependent and can be influenced by developmental stage and disease states. Aberrant expression of Lewis X antigens, in which FUT4 contributes, has been reported in certain cancers and inflammatory conditions, making it a topic of interest in studies of glycosylation changes and disease progression.

Clinical relevance and research interest around FUT4 center on its role in glycan remodeling and its contributions to adhesion-dependent processes. While it is not a primary diagnostic marker, alterations in FUT4 activity and Lewis X expression are investigated for potential diagnostic or therapeutic implications related to immune function and cancer metastasis.

See also: Lewis blood group antigens, fucosyltransferase family, selectins.