Optical Manipulation of Subcellular Protein Translocation Using a Photoactivatable Covalent Labeling System

Abstract The photoactivatable chemically induced dimerization (photo‐CID) technique for tag‐fused proteins is one of the most promising methods for regulating subcellular protein translocations and protein–protein interactions. However, light‐induced covalent protein dimerization in living cells has yet to be established, despite its various advantages. Herein, we developed a photoactivatable covalent protein‐labeling technology by applying a caged ligand to the BL‐tag system, a covalent protein labeling system that uses mutant β‐lactamase. We further developed CBHD, a caged protein dimerizer, using caged BL‐tag and HaloTag ligands, and achieved light‐induced protein translocation from the cytoplasm to subcellular regions. In addition, this covalent photo‐CID system enabled quick protein translocation to a laser‐illuminated microregion. These results indicate that the covalent photo‐CID system will expand the scope of CID applications in the optical manipulation of cellular functions.