This family includes the NgoBV (recognises GGNNCC but cleavage site is unknown) restriction endonuclease.

1: Restriction and modification systems of Neisseria gonorrhoeae. Stein DC, Gunn JS, Radlinska M, Piekarowicz A; Gene. 1995;157:19-22. PMID:7607490

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