This video describes BiFC-PALM ― a combination of photoactivated localization microscopy and bimolecular fluorescence complementation ― to assess protein-protein interactions. BiFC involves the fusion of two fluorescent protein fragments with two interacting proteins of interest. When the two proteins interact, the fragments are brought into proximity, which allows the two parts to come together and reconstitute a functional fluorescent protein. The fluorescence of a single fluorophore is localized at a single molecule level inside cells by PALM.
Protocol
1. Cloning Determine the configurations to clone and choose a linker. Tag proteins with the fragments on the N- or C-terminus as described below so they do not disrupt their proper localization. Use a flexible linker such as (GGGGS)x2. Genetically tag the proteins of interest to the PAmCherry1 fragments. As one option, use the cloning plasmids listed in the Materials List containing the fragments RN (PAmCherry1 residues 1-159) and RC (Met plus PAmCherry1 residues 160-236) with flanking MCS sequences…