The human metabolic network. A) The full reaction network used in this analysis. Colors correspond to the compartment in which each reaction occurs. The network was visualized with Gephi 0.7  using the Force-Atlas layout algorithm. B) Schematic view of network construction. Reactions that share a metabolite are joined by edges. Each reaction in A may also be associated with one or more genes; it is these genes for which we calculate the selective constraint.
Hudson and Conant BMC Evolutionary Biology 2011 11:89 doi:10.1186/1471-2148-11-89