Figure 3.

Structures bearing terminal mannose predominate the surface of Detroit 562 pharyngeal cells as determined by PGC-LC-ESI-MS/MS. (A) Surface N-glycans are primarily oligomannose structures. (B) Mannose is the most abundant terminal monosaccharide of N-glycans. (C) Examples of oligomannose, complex, and hybrid N-glycans are provided, including relative abundance and mass-to-charge ratio (m/z) as detected by MS. Structures were identified primarily using MS² spectra (D–F) [28,29,30,31] in addition to precursor mass:charge ratio (m/z) and retention time. Structural isomers sharing the same m/z, composition, and terminal monosaccharide presentation were combined in evaluation of abundance, calculated by integration of area under of the curve from extracted ion chromatograms. Abundance values are relative and are presented as combined mean ± SEM from 3 biological replicates, each with 3 technical replicates. * Denotes doubly charged fragments. Glycans are represented using conventional graphical nomenclature [32].