Figure 15.7 ATP has a central position in phosphoryl-transfer reactions. The role of ATP as the cellular energy currency is illustrated by its relation to other phosphorylated compounds. ATP has a phosphoryl-transfer potential that is intermediate among the biologically important phosphorylated molecules. High-phosphoryl-transfer-potential compounds derived from the metabolism of fuel molecules are used to power ATP synthesis. In turn, ATP donates a phosphoryl group to other biomolecules to facilitate their metabolism.