 The TAP tag consists of calmodulin binding peptide (CBP) from the N-terminal, followed by a TEV protease cleavage site and two Protein A domains, which bind tightly to IgG (making a TAP tag a type of epitope tag).Many other tag/bead/eluent combinations have been proposed since the TAP principle was first published.This tag is also known as the C-terminal TAP tag because an N-terminal version is also available.