Figure 5
From: The CTCF insulator protein forms an unusual DNA structure
The CTCF zinc finger domain is responsible for the formation of the unusual DNA structure. (A) Electrophoretic mobility shift assays were performed using the purified zinc finger domain and radiolabeled permuted probes containing the β-globin chicken FII insulator element in the reverse orientation. The zinc finger domain exhibits the similar mobility pattern when bound to the FII probes, as does the full length CTCF (see Figure 2B). The extraneous bands running behind the CTCF-DNA complexes in the MluI, NheI, and SpeI lanes are present in the probes in the absence of added CTCF and are of unknown origin. (B) The experiment was repeated with the radiolabeled permuted probes containing the chicken F1 lysozyme silencer element. Once again, the zinc finger domain is sufficient for the formation of the unusual DNA structure. Note that the complexes of CTCF with probes generated by digest with MluI, BglII and NheI show an increased mobility at the F1 element while the remaining probe-CTCF complexes show a decreased electrophoretic mobility in the native gel.