A generic protein purification method for protein complex characterizationand proteome exploration

We have developed a generic procedure to purify proteins expressed at their natural level under native conditions using a novel tandem affinity purifi cation (TAP) tag. The TAP tag allows the rapid purification of complexes fr om a relatively small number of cells without prior knowledge of the comple x composition, activity, or function. Combined with mass spectrometry, the TAP strategy allows for the identification of proteins interacting with a g iven target protein. The TAP method has been tested in yeast but should be applicable to other cells or organisms.