EcorI ~1,000 dimer copies/cell: EcorV 100 dimer copies/cell copies/cell
||Bacteria Escherichia coli
||Pollak AJ, Chin AT, Reich NO. Distinct facilitated diffusion mechanisms by E. coli Type II restriction endonucleases. Biochemistry. 2014 Nov 18 53(45):7028-37. doi: 10.1021/bi501110r. p.7035 right column 2nd paragraphPubMed ID25350874
|| Modrich P, Zabel D. EcoRI endonuclease. Physical and catalytic properties of the homogenous enzyme. J Biol Chem. 1976 Oct 10 251(19):5866-74.  Ichige A, Kobayashi I. Stability of EcoRI restriction-modification enzymes in vivo differentiates the EcoRI restriction-modification system from other postsegregational cell killing systems. J Bacteriol. 2005 Oct187(19):6612-21. DOI: 10.1128/JB.187.19.6612-6621.2005  Bougueleret L, Tenchini ML, Botterman J, Zabeau M. Overproduction of the EcoR V endonuclease and methylase. Nucleic Acids Res. 1985 Jun 11 13(11):3823-39.PubMed ID786985, 16166522, 2989776
||P.7035 right column 2nd paragraph: "Relative protein expression levels may help to explain why EcoRI and EcoRV have different translocation properties but still can individually effectively cleave phage DNA. In E. coli, EcoRI has ∼1000 dimer copies (primary sources 43, 44), whereas EcoRV has only 100 dimer copies (primary source 45). Due to its sliding mechanism, each EcoRI enzyme is confined to a smaller region of DNA, however, the abundance of protein copies extends its occupancy along DNA (Figure 8). Although rarer, each EcoRV enzyme can extend its footprint to more distant regions of DNA. These two distinct translocation mechanisms may function synergistically to ensure phage defense. Importantly, the drawback of one of these translocation mechanisms is mitigated by the other, creating a robust phage restriction strategy."