Dual-specificity phosphatase

Dual-specificity phosphatase (DUSP; DSP) is a form of phosphatase that can act upon tyrosine or serine/threonine residues. Dual-specificity phosphatase (DUSP; DSP) is a form of phosphatase that can act upon tyrosine or serine/threonine residues. There are several families of dual-specificity phosphatase enzymes in mammals. All share a similar catalytic mechanism, by which a conserved cysteine residue forms a covalent intermediate with the phosphate group to be eliminated. The residues surrounding their catalytic core obey a rather strict consensus: His-Cys-x-x-x-x-x-Arg-Ser. The serine side chain and an additional conserved aspartate play a central role in the elimination of the Cys-linked intermediate, thus completing their enzymatic cycle. The main difference between tyrosine-specific phosphatases and dual-specificity phosphatases lies in the width of the latter enzymes' catalytic pocket: thus they can accommodate phosphorylated serine or threonine side chains as well as phosphorylated tyrosines. The human genome encodes at least 61 different DUSP proteins. The following major groups or families of DUSPs were identified: There are three members of this family (SSH1L, SSH2L and SSH3L) with broad specificity. They contain SH3-binding motifs as well as F-actin binding motifs, thus they are generally believed to play a role in the regulation of cytoskeletal rearrangements. In accordance with their proposed rule, proteins like ADF, cofilin and LIMK1 are slingshot substrates.