An Economical High‐Throughput “FP‐Tag” Assay for Screening Glycosyltransferase Inhibitors

O-GlcNAc transferase (OGT) involves in many cellular processes and selective OGT inhibitors are valuable tools to investigate O-GlcNAcylation functions, and could potentially lead to therapeutics. However, high-throughput OGT assays that are suitable for large-scale HTS, and can identify inhibitors targeting both acceptor, donor sites, and allosteric binding-sites are still lacking. Here, we report the development of a high-throughput "FP-Tag" OGT assay with bovine serum albumin (BSA) as a low-cost and superior "FP-Tag". With this assay, 2-methyleurotinone was identified as a low μM-range OGT inhibitor. This type of assay with BSA as "FP-Tag" would find more applications with other glycosyltransferases.