This family includes the XamI (recognises GTCGAC but cleavage site unknown) restriction endonuclease.

1: A new restriction endonuclease from Streptomyces albus G. Arrand JR, Myers PA, Roberts RJ; J Mol Biol. 1978;118:127-135. PMID:415144

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