Chemical Tools for Decoding the Functions of O-GlcNAcylation

O-GlcNAc has been implicated in the modulation of diverse pathophysiological processes, as thoroughly discussed in other chapters of this book. However, due to the dynamic property of O-GlcNAcylation and its coexistence with different posttranslational modifications, it remains a daunting challenge to obtain natural O-GlcNAcylated proteins as homogeneous forms and decipher O-GlcNAc functions in a site-specific and structurally accurate manner. To address this issue, researchers have developed various tools for better understanding the roles of O-GlcNAc, which can be categorized into two main approaches. The first approach takes advantage of the natural biosynthetic pathways and endogenous proteins and utilizes properly designed chemical probes, inhibitors, or affinity-based constructs to label, manipulate, and profile O-GlcNAcylation. The second approach relies on multiple chemical methods to construct the protein of interest in vitro and subsequently study the synthesized sample bearing well-defined O-GlcNAcylation. This chapter will briefly overview these two aspects of developed tools and their applications.