Figure 2: Illustrating the “looping” model of enhancer function. In this model, the promoter and enhancer, which are separated by a large distance, are brought into close physical proximity by “looping” out the intervening DNA segment. This allows direct, physical contact between the two DNA elements and their associated epigenetic marks and bound proteins. In this example, the enhancer is marked by H3K4me1, and co-occupied by a transcription factor (TF) and Cyclic AMP-responsive element binding protein (CBP). The promoter is marked by H3K4me3, indicating it is actively transcribed by RNA Pol II (Pol II). The DNA loop is stabilized by the cohesin complex.