Chapter 10 Protein Glycosylation in Insects

Publisher Summary This chapter discusses the protein glycosylation in insects. Isolated plasma membrane glycoprotein fractions were investigated for their affinity towards immobilized Concanavalin A and Soybean Agglutinin, analyzed for their monosaccharide compositions and treated with endo-and exoglycosidases. The basic structural features, especially in the presence of the Man 3 GlcNAc 2 core pentasaccharide, these glycans resembled those of mammalian origin. The fact that the incorporation of radioactive GalNAc, in contrast to that of GlcNAc, was not affected by tunicamycin, together with the susceptibility of the GalNAc content to β-elimination, suggested this monosaccharide to be part of O-linked carbohydrate. No evidence could be found for the presence of sialic acids in the GalNAc-containing glycans. The evidence so far available suggests that the precursor oligosaccharide assembly in insect cells, although not yet fully elucidated, proceeds along the same routes as has been worked out for mammalian organisms, involving dolichyl phosphates as lipid carriers.