Fig. 4.

Evolutional acquisition of the GTP sensing function through rewiring of the functional cellular network. (Left) Ancestral PI5P4K only is connected to the ATP-energy network, and fluctuation in the ATP concentration was largely attenuated in the PI5P4K network to show the basal activity. (Right) Two critical mutations introduced the novel functional connection to the GTP-energy network, which allows the endowing of the novel GTP responsiveness to the PI5P4K network and a novel function to the cell.