Figure 1
From: Asymmetric relationships between proteins shape genome evolution
Simple examples of asymmetric relationship between reactions A and B (A→B). Nodes and arrows indicate metabolites and metabolic reactions, respectively. At steady-state the activity (that is, carrying a flux) of reaction A depends on the activity of B, but the activity of B is independent of the activity of A, because there is an alternative converging or diverging flux (dashed arrows).