Cell migration is a process that is controlled by the formation and correct localization of protein complexes and by post-translational modification of individual proteins. Forster or fluorescent resonance energy transfer (FRET) detected using fluorescence lifetime imaging microscopy (FLIM) provides a method by which protein–protein interactions may be detected and spatially localized within a cell. This technique can be used to map protein activation states and the formation and dissolution of protein complexes that control movement of a cell. This chapter describes a protocol for detecting FRET between GFP- and mRFP1-tagged proteins in fixed adherent cells. A background to both FRET and FLIM is provided followed by an overview of the method and a full protocol for sample preparation, data acquisition, and analysis.
