Comparison of the N-glycomes of D. purpureum and D. discoideum cells. Cells were harvested from co-cultures with Klebsiella aerogenes, and N-glycans were released from total CHAPS-solubilized, pepsin-digested protein using PNGase A [59, 60]. (a) Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF)/TOF mass spectrometry spectrum of underivatized D. discoideum N-glycans. (b) Corresponding spectrum from D. purpureum. Structure assignments are based on glycan compositions derived from m/z values (H = Hex, N = HexNAc, F = Fuc), tandem mass spectrometry analysis, linkage analysis and exoglycosidase digestions. Brackets indicate uncertainties in the positions of peripheral GlcNAc (= N) and mannose (= H) residues. The major ions are [M + Na]+; minor [M + K]+ ions are also present. D. purpureum N-glycans lack α3-linked core fucose and the fourth peripheral β4-linked GlcNAc consistent with the absence of CAZy GT10 and GT17 genes predicted to encode the glycosyltransferases responsible for these peripheral modifications in D. discoideum (Table S16 in Additional file 1). A.u., arbitrary units.