Figure 7

Properties of the inferred hierarchical structure for the yeast phosphorylome generated by HSM algorithm. (A) The distribution of feed-forward loop (FFL) motifs in the hierarchical network. In a FFL motif, a kinase X phosphorylates another kinase Y and both target a common substrate Z. Depending on the location of X and Y in the hierarchical structure, the X-- > Y interaction can be categorized into nine combinations. Downward interactions (TM, TB, and MB), upward interactions (MT, BT, and BM), and horizontal interactions (TT, MM, and BB) are shown with red, blue, and gray bars, respectively. (B) The Venn diagram of substrates of kinases at different levels.