Protein phosphatases are signal transducing enzymes that dephosphorylate intracellular proteins phosphorylated on serine, threonine and tyrosine residues by protein kinases.
The activities of the cognate protein kinase or phosphatase acting on a particular site are tightly regulated. Protein phosphatases regulate the level and extent of protein phosphorylation. Concomitant control of kinases and phosphatases provides the cell with the capacity to rapidly switch proteins from their phosphorylated to dephosphorylated state to meet differing physiological demands. Deregulation of protein phosphatases has been linked to various disease states including cancer and diabetes.
The protein tyrosine phosphatase PTP-1B has been shown to be a negative regulator of the insulin signalling pathway, suggesting that inhibitors of this enzyme may be beneficial in the treatment of type 2 diabetes.