Extended Data Fig. 3. Quantification of IFNγR2(T168N) glycoforms by mass spectroscopy.

a, The mutant IFNγR2(T168N) protein was expressed in HEK293S GnTI⁻ cells and purified by SEC. The SEC profile is shown (left) with the corresponding fractions on SDS–PAGE (right). Lane 1 shows the sample loaded on the SEC column, lane 2 shows the Mark 12 protein ladder, and lanes 3–9 are fractions 14–20. Data are representative of at least 3 biologically independent experiments. b, The protein coverage map shows sequence coverage of 76.82% for the entire IFNγR2(T168N) protein including the peptide of interest, containing N168, which is underlined. This peptide was detected as a glycopeptide with several glycoforms as quantified in Fig. 3d. Mappings highlighted in green indicate high confidence with a false discovery rate (FDR) below 1% and yellow indicates a FDR of 1–5%. Carbamidomethyl (C) and glycosylation (G) sites are indicated above the site of modification. Confidence levels were determined as previously described³⁸. c, MS2 spectra confirming that the ion used for the EICs shown in Fig. 3d is the peptide SSPFDIADNSTAF from IFNγR2(T168N) modified with a HexNAc2Hex5 glycan attached to N168. The data shown are for a single experiment.