The phosphatome of an organism is the set of phosphatase genes in its genome. Phosphatases are enzymes that catalyze the removal of  phosphate from biomolecules. Over half of all cellular proteins are modified by phosphorylation which typically controls their functions. Protein phosphorylation is controlled by the opposing actions of protein phosphatases and protein kinases.
Most phosphorylation sites are not linked to a specific phosphatase, so the phosphatome approach allows a global analysis of dephosphorylation, screening to find the phosphatase responsible for a given reaction, and comparative studies between different phosphatases, similar to how protein kinase research has been impacted by the kinome approach.