[Phosphorylation as a method of regulating inorganic pyrophosphatase activity in E. coli. I. Phosphorylation and...

ATP phosphorylates the regulatory center of E. coli inorganic pyrophosphatase with the resultant 1,5-fold increase in the activity of the enzyme. The maximal incorporation of the ATP gamma-group into pyrophosphatase is 3 moles per mole of the protein. Pi likewise phosphorylates the enzyme regulatory center and lowers the pyrophosphatase activity by 10-15%. The ATP- and Pi-mediated phosphorylation processes are interrelated; ATP prevents phosphorylation by Pi and brings about rapid dephosphorylation of Pi-modified protein.