Development of a split SNAP-tag protein complementation assay for visualization of protein-protein interactions in living cells

A split SNAP-tag protein complementation assay was developed for visualization of protein-protein interactions in living cells. Split SNAP-tagms, fragments of divided SNAP-tag between amino acid residues 91 and 92, were fused to proteins that can interact with each other. After incubation with a fluorescent SNAP-tag substrate, cells that expressed split SNAP-tag fusion proteins generated fluorescent signals when these proteins interacted. Moreover, by combination with the split CLIP-tag (SNAP-tag mutant), simultaneous labeling was achieved. This split SNAP-tag labeling method should be a useful tool for visualization of protein-protein interaction processes.