This family includes the HaeII (recognises and cleaves RGCGC^Y) restriction endonuclease.

1: [Testing and isolation of high-purity restriction endonucleases]. Puchkova LI, Ushakova TA, Mikhailova VK, Serov GD, Krivopalova GN, Repin VE; Prikl Biokhim Mikrobiol. 2002;38:20-24. PMID:11852561

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