Members of this family are predominantly found in prokaryotic restriction endonuclease FokI, and adopt a structure consisting of an alpha/beta/alpha core containing a five-stranded beta-sheet. They recognise the double-stranded DNA sequence 5'-GGATG-3' and cleave DNA phosphodiester groups 9 base pairs away on this strand and 13 base pairs away on the complementary strand [1]. This entry represents the C-terminal cleavage domain of FokI.

1: Structure of FokI has implications for DNA cleavage. Wah DA, Bitinaite J, Schildkraut I, Aggarwal AK; Proc Natl Acad Sci U S A. 1998;95:10564-10569. PMID:9724743

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