Another virtue of FLAG is that the longest trypsinogen prosequences are of this length. This enables the removal of the tag and the production of an authentic N-terminus of the fusion protein partner by enterokinase treatment. The protease recognizes the five C-terminal amino acids of the marker peptide AspAspAspAspLys as minimal specificity site. The FLAG peptide can be fused to either the N- or C-terminus of a given fusion protein. Nevertheless, the N-terminal fusion has several advantages.