The O-fucosyltransferase O-fut1 is an extracellular component that is essential for the constitutive endocytic trafficking of Notch in Drosophila.

Notch is a transmembrane receptor that mediates the cell-cell interactions necessary for many cell-fate decisions. Endocytic trafficking of Notch plays important roles in the activation and downregulation of this receptor. A Drosophila O-FucT-1 homolog, encoded by O-fut1, catalyzes the O-fucosylation of Notch, a modification essential for Notch signaling and ligand binding.