Epitope tags provide a method to localize gene products in a variety of cell types, study the topology of proteins and protein complexes, identify associated proteins, and characterize newly identified, low abundance or poorly immunogenic proteins when protein specific antibodies are not available. Tandem affinity purification (TAP) is an affinity purification method for isolation of TAP-tagged proteins together with associated proteins. The protocol involves the fusion of the "TAP tag" (typically a calmodulin binding peptide (CBP), a tobacco etch virus protease (TEV protease) cleavage site and Protein A) to the protein of interest. The TAP technique is useful in analyzing in vivo interactions.
Tobacco Etch Virus