CSC technology: selective labeling of glycoproteins by mild oxidation to phenotype cells.

Cell surface glycoproteins represent important markers for the phenotyping of healthy and malignantly transformed cells. The mass spectrometry-based cell surface capturing (CSC) technology allows for extensive multiplexed identification and relative quantification of glycoproteins expressed on the cell surface at a given point in time. CSC technology is based on the mild oxidation of glycans from cell surface proteins on living cells. Oxidized glycans are tagged with a bifunctional linker molecule and glycopeptides are subsequently enriched by affinity chromatography. Here, we describe a step-by-step protocol of the CSC technology, which not only enables the identification of cell surface glycoproteins, but also the concurrent determination of protein N-glycosylation sites.