Transposons are mobile DNA sequences capable of replication and insertion into the chromosome. Typically transposons code for the transposase enzyme, which catalyzes insertion, found between terminal inverted repeats. Tn5 has a unique method of self- regulation in which a truncated version of the transposase enzyme acts as an inhibitor. The catalytic domain of the Tn5 transposon is found in pfam01609. This domain mediates dimerization in the known structure.