Members of this family adopt a secondary structure consisting of nine alpha-helices, six 3-10 helices and 13 beta-strands. They bind two GCC-CGG recognition sequences to cleave DNA into blunt-ended products [1].

1: Crystal structure of NaeI-an evolutionary bridge between DNA endonuclease and topoisomerase. Huai Q, Colandene JD, Chen Y, Luo F, Zhao Y, Topal MD, Ke H; EMBO J. 2000;19:3110-3118. PMID:10856254

2: Sequence, structure and functional diversity of PD-(D/E)XK phosphodiesterase superfamily. Steczkiewicz K, Muszewska A, Knizewski L, Rychlewski L, Ginalski K; Nucleic Acids Res. 2012;40:7016-7045. PMID:22638584