This family of proteins includes the restriction endonucleases MvaI and BcnI. These enzymes both function as monomers. MvaI cleaves the sequence CC/WGG, where W is an A or a T nucleotide, leaving sticky ends. BcnI cleaves the sequence CC/SGG, where S is G or C, leaving sticky ends [1-2].

1: Restriction endonuclease MvaI is a monomer that recognizes its target sequence asymmetrically. Kaus-Drobek M, Czapinska H, Sokolowska M, Tamulaitis G, Szczepanowski RH, Urbanke C, Siksnys V, Bochtler M; Nucleic Acids Res. 2007;35:2035-2046. PMID:17344322

2: Monomeric restriction endonuclease BcnI in the apo form and in an asymmetric complex with target DNA. Sokolowska M, Kaus-Drobek M, Czapinska H, Tamulaitis G, Szczepanowski RH, Urbanke C, Siksnys V, Bochtler M; J Mol Biol. 2007;369:722-734. PMID:17445830

3: 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