Tandem affinity purification (TAP) is a purification technique for studying protein–protein interactions. It involves creating a fusion protein with a designed piece, the TAP tag, on the end. The original TAP method involves the fusion of the TAP tag to the C-terminus of the protein under study. The TAP tag consists of calmodulin binding peptide (CBP) from the N-terminal, followed by tobacco etch virus protease (TEV protease) cleavage site and Protein A, which binds tightly to IgG. The relati