Phosphatases in the Akt Pathway
Protein phosphorylation is a reversible and dynamic post-translational modification that is governed by the opposing activities of phosphatases and kinases. Protein phosphatase enzymes remove phosphate groups that have been covalently attached to serine, threonine, and tyrosine residues by protein kinase enzymes. Alternatively, lipid phosphatases such as PTEN remove phosphate groups from lipid substrates. By counteracting the activities of kinases, phosphatases play an important role in the control of a wide variety of cellular functions including cell cycle checkpoints, responsiveness to growth factors, contact inhibition, and cellular motility. The phosphatases listed below are associated with the Akt signaling pathway, which regulates cell growth, survival, proliferation, autophagy, and metabolism. Since dysregulation of the Akt pathway is generally oncogenic, phosphatases that reverse the phosphorylation events in this pathway tend to be tumor suppressors.