Native mass spectrometry for proximity-inducing compounds: a new opportunity for studying chemical-induced protein modulation

Introduction: Proximity-inducing compounds promote protein-protein interactions by bringing proteins into close spatial alignment. Among them, targeted protein degradation (TPD) compounds are noteworthy for their potential to target previously ‘undruggable’ proteins. Native mass spectrometry (nMS), a technique that enables the detection of non-covalent interactions, is emerging as a key tool for studying compound-induced ternary complex formation. Areas covered: This review highlights the use of nMS in unraveling the mechanisms of proximity-inducing compounds, focusing on all available studies published since 2020, identified through a PubMed database search. The authors explore how nMS helps investigate the efficacy and mechanisms of proteolysis-targeting chimeras (PROTACs) and molecular glues by capturing the binary and ternary complexes formed by E3 ligases, protein of interest (POI), and these molecules. Expert opinion: nMS excels at analyzing intact protein complexes, providing real-time insights into interactions between E3 ligases, POIs, and proximity-inducing agents. This analysis helps understand the formation, stability, and dynamic nature of the complexes along with precise data on stoichiometry and binding affinities, which are crucial for selecting and refining effective degraders. The future of nMS in TPD research is promising, with potential applications in kinetic analysis, degrader screenings, and exploration of novel E3 ligases and target proteins.