Figure 3

(a) Z-score for the sign packing index (see Supplementary Notes in Additional File 1 for a definition). The 4 transcriptional networks have sign arrangements on the nodes that are significantly asymmetric, hence improving their frustration index. (b) Representation of the sign packing property on the E.coli transcriptional network. The nodes significantly enriched in either positive or negative edges are shown in green (the size is proportional to their connectivity). The distribution of negative edges (dashed) is shown in (c). This graph should be compared with the random sign assignment of Fig. S6.