This family includes transposases of Tn3, Tn21, Tn1721, Tn2501, Tn3926 transposons from E-coli. The specific binding of the Tn3 transposase to DNA has been demonstrated. Sequence analysis has suggested that the invariant triad of Asp689, Asp765, Glu895 (numbering as in Tn3) may correspond to the D-D-35-E motif previously implicated in the catalysis of numerous transposases [2].

1: Purification of the Tn3 transposase and analysis of its binding to DNA. Fennewald MA, Gerrard SP, Chou J, Casadaban MJ, Cozzarelli NR; J Biol Chem 1981;256:4687-4690. PMID:6262296

2: Catalytic center quest: comparison of transposases belonging to the Tn3 family reveals an invariant triad of acidic amino acid residues. Yurieva O, Nikiforov V; Biochem Mol Biol Int 1996;38:15-20. PMID:8932514