Distribution of autoregulation.

(A) Sensing specificity (presence/absence of external regulation) and response specificity (regulon size). (B–D) Abundance of autoregulation in three TF response specificity classes quantified by regulon size. This includes first an analysis including all network TFs (B), followed by two more examinations considering those subsets of TFs without (C) or with (D) upstream transcriptional control, respectively. Classes: low (one to four regulated operons), medium (five to nine) or high (ten or more, considered as TF hubs). We also plotted the null behavior obtained by random sampling of the corresponding class –preserving group size– within the specific TF group (B,C, or D), 10 000 times (mean, continuous gray line, ±2 standard deviations, shaded area). Lines between points to help visualization. (E) Autoregulated TFs with upstream regulation as part of a FFL, a motif constituted by three elements X, Y, and Z, two of them being always a TF in this context (X and Y). In (D), the ratio of autoregulated Y for each specificity class is also showed (orange), see main text.