LAUSR

O‐GlcNAc transferase (OGT) and O‐GlcNAcase (OGA) are the only enzymes that regulate the dynamics of protein O‐GlcNAcylation. Protein O‐GlcNAcylation is an important post‐translational modification (PTM) of nuclear and cytoplasmic proteins with O‐linked β‐N‐acetyl‐glucosamine (O‐GlcNAc). O‐GlcNAc and its enzymes are involved in a wide variety of cellular processes and are linked to the pathological progression of chronic diseases. Considering their emerging biological significance, systematic and rapid methods to determine the activities of OGT and OGA have become essential, and several chemical/biochemical methods for measuring the activities of these enzymes have been developed. This minireview mainly focuses on the various biochemical assay methods developed to date, while also providing a description of the fundamental principles underlying the monitoring of O‐GlcNAc enzyme activities.