Fig. 5.

Modeling chromatin loops in transgenic lines of drosophila. (A) A loop formed by identical insulators brings the enhancer closer to the promoter. (B) A tight loop between the two insulators blocks the enhancer it contains. (C) Increased distance between the insulators surrounding the enhancer neutralizes the insulation. (D) Loops formed by the three insulators do not interfere with activation of the reporter gene transcription. (E) Mutual orientation of insulators (indicated with arrows) determines the configuration of the chromatin loop and, as a consequence, the possibility of transcription activation. Designations: G4 – yeast activator GAL4; other designations are the same as those in Fig. 2.