Tandem Affinity Purification (TAP)

TAP is an affinity purification strategy for the efficient isolation and characterization of native protein complexes. Isolation and dissection of native multiprotein complexes is a central theme in functional genomics. The development of the tandem affinity purification (TAP) tag has enabled an efficient and large-scale purification of native protein complexes. The original TAP tag features a size of 21 kDa and requires time consuming cleavage. By combining a tandem Strep-tag II with a FLAG-tag , the size of the TAP (SF-TAP) tag is reduced to to 4.6 kDa. Both tags have a medium affinity and avidity to their immobilized binding partners. This allows the elution of SF-tagged proteins under native conditions using desthiobiotin in the first step and the FLAG octapeptide in the second step. The SF-TAP protocol represents an efficient, fast and straightforward purification of protein complexes from mammalian cells.