Detection of Membrane Protein Interactions by Cell-based Tango Assays.

The Tango assay is a protein-protein interaction assay, in which a transcription factor (rTA) is fused to a membrane-bound protein via a linker that contains a cleavage site for TEV protease, whereas a soluble interaction partner is fused to TEV protease (Barnea et al., 2008). Association between the two interaction partners leads to an efficient cleavage of the transcription factor, allowing it to translocate to the nucleus and activate a luciferase reporter gene as measurement of the interactions. In this modified assay, we fused one copy of the membrane-spanning amyloid precursor protein (APP) C99 region to TEV site-rTA (C99-TEV site-rTA) and a second copy to TEV protease (C99-TEV) to analyze intramembrane C99-C99 interaction in live cells.