Reversible Inhibition of Tyrosine Protein Phosphatases by Redox Reactions

Abstract

Protein phosphorylation/dephosphorylation is considered a widespread mechanism of protein regulation. The covalent addition of a phosphate group to tyrosine residues in cellular proteins may occur as an appropriate response to a series of morphological and biochemical processes, with particular importance in complex functions such as growth, proliferation, differentiation, adhesion and motility. Protein tyrosine phosphorylation is regulated in the cell by the opposing activities of two classes of enzymes: protein tyrosine kinases, which phosphorylate specific tyrosine residues in protein using ATP as the phosphate source, and protein tyrosine phosphatases, which hydrolyze the phosphotyrosines yielding the restored amino acid residue and inorganic phosphate as products (Kolmodin & Aqvist, 2001; Mayer, 2008). The number of active protein phosphatases with the ability to dephosphorylate phosphotyrosine are very similar to the number of active tyrosine phosphatases. Both types of enzymes also display comparable tissue distribution patterns (Alonso et al., 2004). Abnormalities in tyrosine phosphorylation play a role in the pathogenesis of numerous inherited and acquired human diseases from cancer to immune deficiencies (Alonso et al., 2004)