The addition of O-linked-β-N-acetylglucosamine (O-GlcNAc) onto serine and threonine residues of nuclear and cytoplasmic proteins is an abundant and unique post-translational modification that plays a critical role in governing important biological processes. Since its discovery, O-GlcNAcylation has been shown to contribute to numerous cellular processes, including signaling, protein localization and stability, transcription, chromatin remodeling, mitochondrial function, and cell survival. O-GlcNAcylation is a dynamic and reversible post-translational modification that regulates protein function in a site-specific manner, making it an important player in the regulation of diverse biological processes. Dysregulation of O-GlcNAcylation has been implicated in the pathogenesis of various diseases, including cancer, neurodegenerative disorders, and diabetes. To better understand the regulatory roles of O-GlcNAcylation in cellular physiology and disease pathogenesis, O-GlcNAc proteomics strategies and more specialized, more exact research tools are needed to further explore the bio-functional systematization of O-GlcNAcylation. In recent years, the field of chemical biology has developed various tools and methods for analyzing O-GlcNAc glycosylation, including small molecule sugar probes, metabolic labeling reagents, chemoenzymatic techniques, specific antibodies, and lectins. These tools have served as a foundation for the further development of O-GlcNAc glycoproteomic research strategies. O-GlcNAc glycoproteomic strategies, such as high-resolution mass spectrometry-based approaches have been developed to allow for the detection and quantification of O-GlcNAc modifications on specific proteins, enabling site-specific analysis of O-GlcNAc modification patterns. The number of proteins modified by O-GlcNAc is quite extensive, with at least 7000 modification sites identified in human cells. This highlights the importance of O-GlcNAcylation in regulating diverse biological processes. Identification of O-GlcNAcylation sites with specific biological functions is still a remaining problem. Innovative solutions are required to address this challenge in cell models and disease therapy. At the same time, with the aid of high-resolution mass spectrometry, a large number of O-GlcNAc modification sites on proteins have been identified, which has greatly promoted the study of site-specific O-GlcNAc biological functions. This article has reviewed the recent advances in the field of O-GlcNAc research, with the aim of providing a basis for the development of more chemical tools and offering new research ideas and strategies for uncovering the functions of O-GlcNAcylation in disease progression.

Key words: O-GlcNAcylation, chemical biology, molecular tools, glycoproteomics