FIGURE 4.

The RFTS domain is an endogenous inhibitor of Dnmt1 activity. A, schematic of the GlaI-coupled Dnmt1 assay. B, time and Dnmt1 dependence of the GlaI-coupled assay with 20 nm DNA substrate. With the RFTS domain-lacking protein (amino acids 621–1616), robust increases in fluorescence that were dependent on the concentration of Dnmt1 were observed. C, autoinhibition of RFTS domain-containing Dnmt1. At 20 nm DNA substrate, 2 nm RFTS domain-lacking Dnmt1 construct (amino acids 621–1616) neared completion in 30 min, whereas no reaction progress was observed with 2 nm RFTS domain-containing Dnmt1 construct (amino acids 351–1616). RFU, relative fluorescence units.