Phosphoproteomic studies in bacteria have shown that over 50% of bacterial phosphorylation events occur on metabolic enzymes. Signaling pathways may have thus initially evolved to regulate metabolism. Interestingly, some of these phosphorylation sites on metabolic enzymes identified in bacteria have also been identified by mass spectrometry in mammals. Since these phosphorylation events are conserved throughout evolution, we hypothesize that they are important connection points for metabolic regulation by signaling pathways. We are currently studying these conserved modification sites and their affect on enzyme activity and metabolic flux.