Fig. 4. Identification of N-sialoglycosylation sites in the secretome, on the cell surface and in membrane proteins of HEK293T cells by LC-MS-based proteomics techniques and clustering of N-sialoglycoproteins. (a) MS2 spectrum of the N-sialoglycopeptide LLIAGTN*SSDLQQILSLLESNK (* refers to the N-sialoglycosylation site), from the SLC3A2 protein. (b) Comparison of N-sialoglycosylation sites identified in the secretome, on the cell surface and in membrane protein sample. (c) Comparison of N-sialoglycoproteins identified in the secretome, on the cell surface and in the membrane protein sample. (d) Molecular function analysis of cell surface N-sialoglycoproteins identified in this work.
