FUT8 is the sole enzyme responsible for the N-acetylglucosaminyltransferase GnT I-independent core fucosylation pathway. In a a stable HEK-293S GnT I-/- cell line with either knockdown of FUT8, the erythropoietin produced shows the pure Man5GlcNAc2 glycoform, whereas that produced from the FUT8-overexpressing cell line is fully core-fucosylated oligomannose glycan (Man5GlcNAc2Fuc)
FUT8 potentially forms homodimers in vivo via intermolecular hydrophobic interactions involving alpha-helical domains. alpha-Helical and SH3 domains are all required for enzymatic activity. The SH3 domain locates in close proximity to the alpha-helical domain in an intermolecular manner
the SH3 domain of Fut8, located at the luminal side of the Golgi apparatus, is essential for FUT8 activity both in cells and in vitro. Residue His535 in the SH3 domain is the critical residue for enzymatic activity of FUT8. Ribophorin I (RPN1), a subunit of the oligosaccharyltransferase complex, is an SH3-dependent binding protein of FUT8. RPN1 knockdown decreases both FUT8 activity and core fucose levels