Fucosylation is one of the most common post-translational modifications. Fucosylated glycans are involved in various biological processes, such as cell adhesion, growth factor receptor modulation, microbial and viral infections, cancer and atherosclerosis. These motifs are conserved among a1,2-, a1,6- and O-FucTs, strongly suggesting their implication in the fucose transfer reaction. Site-directed mutagenesis confirmed this hypothesis demonstrating that most of the highly conserved aa in this region are essential for enzymatic activity. Four disulfide bonds may be important for protein folding and stability. A SH3 domain is also present at the C-terminus in all known FUT8 sequences, but its role has not been elucidated yet. Lepidopteran cells can perform most of the post-translational modifications, including N- and O-glycosylation. N-glycan processing is comparable to what observed in mammalian cells during the early stages of the glycosylation pathway with the synthesis of GlcNAcb1,2Mana1,3 Manb1,4GlcNAcb1,4 GlcNAc. The glycan structures most frequently identified on glycoproteins synthesized in GANT61 insect cells are fucosylated paucimannose structures GlcNAc2) and, to a lesser extent, oligomannose-type glycans. The absence of complex oligosaccharides correlates with the absence of b1,4-galactosyltransferase I and sialyltransferases. Despite the in silico identification of a2,6sialyltransferase gene sequences in some lepidopterans, such as Bombyx mori, no sialyltransferase activity has been detected in insect cell lines, such as Sf9 cells. In addition, the very low expression level of Nacetylglucosaminyltransferase I and GNT-II and the Butenafine hydrochloride presence of a Golgi-associated N-acetylglucosaminidase explain the formation of paucimannose structures. In contrast to mammals, two core-fucosylation events with a1,6- and a1,3-linkage have been reported in insects and in plants. Analysis of fucosyltransferase activities in several lepidopteran cell lines showed distinct activities in each cell line. While core a1,3- and core a1,6-fucose are found on glycoproteins expressed in Masmestra brassicae and Trichoplusia ni cell lines, only core a1,6-fucose was found in B mori and Sf9 cells.