The Tango™ Assay technology combines the benefits of the Tango™ assay platform with the highly accurate, sensitive, and live cell GeneBLAzer® Beta-lactamase reporter system. The Tango™ assay measures protein-protein interactions in live mammalian cells. One of the proteins of interest is anchored to cell surface either by its own transmembrane domains or through fusion to CD8 using a "bait" vector provided in this kit. The "bait" vector also provides at its intracellular C-terminus, an in-frame fusion to an exogenous transcription factor, GAL4-VP16. Interposed between the protein of interest and the transcription factor is a specific cleavage sequence for a non-native protease. This chimeric receptor protein is expressed in a cell line containing the beta-lactamase reporter gene responsive to the transcription factor. The "prey" vectors allow an interacting protein to be expressed as a protease fusion protein that recognizes and cleaves the site between the anchored membrane protein and transcription factor. The assay is performed by adding a stimulus to the growing cells for a defined period and measuring the activity of the reporter gene. Activation of the reporter gene provides a quantifiable measurement of the degree of interaction between the anchored membrane protein and the protease-tagged interaction partner and is unaffected by other signaling pathways in the cell, providing an exquisitely specific readout of protein-protein interaction.