Novel Bimolecular Fluorescence Complementation (BiFC) assay for in vivo visualization of the protein-protein interactions and cellular protein complex localizations

Abstract The study of protein-protein interactions (PPIs) is critical for understanding cellular processes within biological systems. The bimolecular fluorescence complementation (BiFC) assay provides a convenient approach for visualization of protein-protein interactions in living cells. A series of fluorescence proteins have been introduced into BiFC system, though new fluorescent proteins need to be brought in this assay. Here, we applied TagBFP2 into BiFC for the first time to verify the interaction between two proteins, and EYFP was set as a positive control. Both fluorescent proteins performed well in our study. Compared to EYFP, the BiFC system based on TagBFP2 showed a higher signal-to-noise ratio, which helps us distinguish the signal of PPIs from noise. With the joining of TagBFP2, we have another color option when we conduct BiFC assay. Especially, the green or yellow channel was occupied by a fluorescent secondary antibody in immunofluorescence application, or an interest protein tagged with a fluorescent protein. BiFC assay presented here is quite easy-to-follow, reliable, and reproducible, which can be completed within 1 week without using costly instruments and technologies that demand a high skill set.