Mapping Polyamine Interactions in Live Cells Through Photoaffinity Labeling

Polyamines are essential metabolites that play a crucial role in regulating key cellular processes. While previous studies have shown that polyamines modulate protein function through non-covalent interactions, the lack of robust analytical methods has limited the systematic identification of these interactions in living cells. To address this challenge, we synthesized novel photoaffinity probes and applied them to a model cell line, identifying over 400 putative protein interactors with remarkable structure-dependent specificity. The interaction profiles of these probes were visualized through in-gel fluorescence scanning, and their subcellular localization was examined using fluorescence microscopy. Higher polyamine analogs predominantly target proteins in the nucleoplasm and cytosol, whereas diamine analogs localize to vesicle-like structures near the Golgi apparatus, implying that different polyamine types show a proclivity for specific cellular compartments. This study provides a comprehensive overview of polyamine-protein interactions in live cells, offering valuable insights into their roles in cellular processes.