The Click-iT™ GalNAz metabolic glycoprotein labeling reagent provides the first part of a simple and robust two-step technique to identify and characterize cell surface O-linked glycoproteins. In step one, cultured cells are incubated with the azide-modified galactosamine (GalNAz). The azido-sugar is metabolically incorporated into cell surface O-linked glycoproteins through the permissive nature of the oligosaccharide biosynthesis pathway. In step two, via the chemoselective ligation or click reaction between an azide and an alkyne, the azido-labeled glycoproteins can then be detected with a Click-iT™ Glycoprotein Detection Kit for gels (TAMRA or Dapoxyl™ alkyne) or Western blots (biotin alkyne). These Click-iT™ products are compatible with LC-MS⁄MS and Multiplexed Proteomics™ technologies for in-depth analyses of the glycoproteome.