Fig. 5.

Identification of CS linkage region glycopeptides derived from human syndecan-4 in Var2CSA enriched fractions from BeWo cells. Representative higher-energy collisional dissociation (HCD) fragmentation spectra of CS glycopeptides carrying hexasaccharide (A-B) and octasaccharide (C-D) linkage region fragments. The octasaccharide structures were characterized by the presence of internal disaccharide fragments HexA-GalNAc at m/z 380.12 in addition to the terminal unsaturated fragment Δ^4,5-unsaturated HexA-GalNAc at m/z 362.11. Hexasaccharides (B) and octasaccharide (D) glycoforms displaying fucose substitution attached to xylose were also detected. Sequence alignment of the amino acid sequences covering the novel SDC4 glycosylation site shows that this glycosite is not well-conserved across multiple mammalian species (E).