Figure 3

Co-localization of spanion clusters and experimental RNA polymerase II sites. The distribution of the distance between the upstream end of a spanionclusters and the downstream end of the closest reported RNA polymerase II sites in upstream position relative to the spanioncluster [16]. The original measurement has been done on confluent HEK cells. In the reference dataset the local spanioncluster patterns of the genes were mapped to the chromosomes using the global coordinates of randomly picked different genes. Real dataset: squares, reference set: continuous line. The distribution is asymmetric due to the way the distance is measured. Alternative metrics were also tested and provided similar results (data not shown). The peak around zero in the reference case reflects to the common general preference of the transcript zero position of the two genetic features. Note that the RNA polymerase II sites span a few hundred bases typically while the most common size of the spanionclusters is around 25 bases. (See Figure 1 and Figure 1 of Sultan et al [16].)