Protein–protein interactions (PPIs) and spatially restricted molecular contacts govern cellular function, yet many are poorly captured by classical biochemical approaches that rely on cell lysis or stable complex isolation. Proximity labeling (PL) technologies have transformed interactome analysis by enabling covalent tagging of biomolecular neighborhoods directly within intact cells, tissues, and living organisms. By generating short-lived reactive species, PL provides spatially and temporally resolved snapshots of molecular organization under native conditions. Recent advances across enzymatic, chemical, and photocatalytic PL platforms have expanded control over labeling radius, kinetics, and activation, while reducing background and enabling microenvironment-specific targeting. Hybrid genetic-chemical and optogenetic strategies further extend PL beyond mapping toward proximity-based signal amplification and functional interrogation. This review focuses on the most significant methodological and conceptual advances in proximity labeling reported over the past two years, highlighting how these developments have enabled discovery of previously inaccessible interaction networks, including membrane assemblies, chromatin complexes, and in vivo protein microenvironments. We conclude by outlining key challenges and future opportunities for proximity labeling in interactome mapping and amplification.
Morgan et al. (Fri,) studied this question.