Golgi recruitment assay for visualizing small-molecule ligand-target engagement in cells

The development of methods that allow detection of ligand-target engagement in cells is an important challenge in chemical biology and drug discovery. Here, we present a Golgi recruitment (G-REC) assay in which the ligand binding to the target protein can be visualized as Golgi-localized fluorescence signals. We show that the G-REC assay is applicable to the detection of various ligand-target interactions, ligand affinity comparison among distinct protein isoforms, and the monitoring of unmodified drug-target engagement in cells.