Fucosylated hybrid-type N-glycans on the secreted human epidermal growth factor receptor from swainsonine-treated A431 cells

N-Glycans linked to the human secreted form of epidermal growth factor rece ptor were isolated from A431 cells after swainsonine treatment. Analysis of the oligosaccharides by H-1 NMR spectroscopy and mass spectrometry shows t he presence of oligomannose- and (alpha 2-3)-sialylated hybrid-type glycans , The major hybrid-type oligosaccharide chains are fucosylated at the Asn-b ound GlcNAc residue. Smaller amounts of the hybrid-type structures are also fucosylated at peripheral GlcNAc residues, constituting the sialyl-le(x) a ntigen. No complex-type glycans are found, suggesting the absence of alpha- mannosidase III. An assay for alpha-mannosidase III on the A431 cells in th e absence and presence of 6 mu M swainsonine shows that Man(5)GlcNAc(2) is not converted into Man(3)GlcNAc(2), thereby confirming that these cells do not contain alpha-mannosidase III activity. (C) 2000 Academic Press.