Photoactivated SOPP3 enables APEX2-mediated proximity labeling with high spatial-temporal resolution in live cells

Proximity labeling (PL) characterizes protein interactome in living cells. However, exogenous H2O2 required for engineered peroxidase, like APEX2, is cytotoxic, while biotin ligases-based PL have poor temporal resolution. Here, we showed that SOPP3, an engineered photosensitizer, could trigger APEX2 mediated PL within seconds under blue light illumination, without exogenous H2O2 or cytotoxicity. This new PL technology paves an avenue to characterize molecular dynamics of key biomedical events with high spatial-temporal resolution, efficiency, and flexible applicability.