O-GlcNAcase is an enzyme responsible for removing O-linked N-acetylglucosamine (O-GlcNAc) modifications from proteins. It works oppositely to O-GlcNAc transferase (OGT), jointly regulating the levels of O-GlcNAcylation within cells. O-GlcNAcase is primarily located in the cytoplasm and nucleus, involved in various biological processes including signal transduction, transcription regulation, stress response, and cell cycle control. Abnormal activity and expression of O-GlcNAcase are associated with the development of diseases such as diabetes and Alzheimer's disease. The gene-specific expression and functional mutations of O-GlcNAcase and their impact on cellular functions are becoming a focus of research.