Photo-lysine captures proteins that bind lysine post-translational modifications

Post-translational modifications (PTMs) have key roles in regulating protein-protein interactions in living cells. However, it remains a challenge to identify these PTM-mediated interactions. Here we develop a new lysine-based photo-reactive amino acid, termed photo-lysine. We demonstrate that photo-lysine, which is readily incorporated into proteins by native mammalian translation machinery, can be used to capture and identify proteins that recognize lysine PTMs, including 'readers' and 'erasers' of histone modifications.