This family includes R.ApaLI and R.XbaI restriction endonucleases. ApaLI recognises and cleaves the sequence GTGCAC.

1: Cloning and expression of the ApaLI, NspI, NspHI, SacI, ScaI, and SapI restriction-modification systems in Escherichia coli. Xu SY, Xiao JP, Ettwiller L, Holden M, Aliotta J, Poh CL, Dalton M, Robinson DP, Petronzio TR, Moran L, Ganatra M, Ware J, Slatko B, Benner J; Mol Gen Genet. 1998;260:226-231. PMID:9862476

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