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[Preprint]. 2021 Feb 10:2021.02.03.429627. Originally published 2021 Feb 4. [Version 2] doi: 10.1101/2021.02.03.429627

Figure 1. O-glycosylation of SARS-CoV-2 spike protein expressed in insect or human cells.

Figure 1.

(a) Experimental strategy. (b) A graphical layout of spike protein sequence annotated with identified O-glycosylation sites using Orbitrap Lumos mass spectrometer with ETD and HCD MS2 fragmentation. Independently identified O-glycosites on HEK 293F-derived ectodomain using Q Exactive HF-X mass spectrometer with HCD MS2 fragmentation are shown with orange outlines. (c) A table summarizing O-glycosites and respective structures found in different S formulations (yellow rectangles). Ambiguous sites are shown as merged rectangles across several positions. “N/A” - not applicable; “-” - not detected. Orbitrap Fusion Lumos derived sites are marked with grey outlines. Additional sites identified on HEK 293F ectodomain with Q Exactive HF-X are marked with orange outlines. (d) Examples of O-glycopeptides identified with Orbitrap Fusion Lumos using ETD fragmentation. MS2 c and z product ion fragments are annotated based on the respective ETD spectra (Fig S1).