Chemoproteomic approach for mapping binding sites of post-translational-modification-mediated protein–protein interactions

Post-translational modifications (PTMs) are involved in essential cellular processes through mediating protein–protein interactions (PPIs). Photoaffinity probes have been developed to elucidate the network of PTM-mediated PPIs. Typically, these probes are designed based on the PTM of interest. Each probe is armed with a photoreactive group that captures its binding proteins upon UV irradiation and a tag that helps to isolate the trapped proteins. ADdis-Cys, a trifunctional unnatural amino acid harboring these two features into a cleavable amino acid, allows a photoaffinity probe to identify PTM-binding proteins and simultaneously map their binding sites by direct enrichment of the crosslinked peptides for mass spectrometry (MS) analysis (ADdis-Cys-MS).