Dephosphorylation
Dephosphorylation is the Covalent modification of a protein, involving the removal of a Phosphate group from the Serine, Threonine or Tyrosine side chain of that protein. It is in inverse correlation with Phosphorylation (the addition of phosphate groups to proteins) as this reaction is involved in undertaking the reverse effect of Protein Kinases, the enzymes involved in phosphorylation. [1]
Protein phosphatases are Enzymes that catalyse the dephosphorylation reaction, during which, activation of the enzyme will result in Hydrolysis of the bond between the phosphate group and the protein, hence removing the phosphate but otherwise leaving the protein unchanged. They can be highly specific or have a wide range of Substrates.
The main function of dephosphorylation in cells is that it reverses the effects of phosphorylation, by turning off the downstream signalling pathways created by kinases. This can be either a stimulatory or inhibitory effect, depending on the whether the kinase is involved in Activation or Inactivation of the protein signalling pathway. [2]