Protein kinases and phosphatases

Protein kinases and phosphatases are a vast group of enzymes that serve as the primary regulators of eukaryotic cell signaling by modulating the phosphorylation state of proteins [Cohen, 2002, Nat Rev Drug Discov]. Kinases add phosphate groups to specific residues, typically altering the target protein's function or creating docking sites for other signaling molecules, while phosphatases remove these groups to terminate the signal [Tonks, 2006, Nat Rev Mol Cell Biol]. This dynamic balance controls critical cellular processes including growth, differentiation, metabolism, and apoptosis. Dysregulation of these enzymes, such as the constitutive activation of kinases or the loss of phosphatase activity, is a central driver in many pathologies, particularly oncology and inflammatory diseases [Bhullar et al., 2018, Mol Cancer]. As such, they represent one of the most important classes of therapeutic targets, with numerous small-molecule inhibitors and biologics currently in clinical use or development. However, the high degree of structural conservation among kinase catalytic domains often presents challenges regarding drug selectivity and off-target effects [Force & Kolaja, 2011, Nat Rev Drug Discov]. Therapeutic strategies often focus on small-molecule inhibitors that compete with ATP or allosterically modulate enzyme conformation. Recent advances also include the development of PROTACs and phosphatase activators to address previously 'undruggable' members of this class.

Other names

Kinome and phosphatomePhosphotransferases and phosphohydrolasesCell signaling enzymesProtein phosphotransferases

Kinases catalyze the transfer of a gamma-phosphate group from ATP to specific amino acid residues (serine, threonine, or tyrosine) on substrate proteins, a process known as phosphorylation [Manning et al., 2002, Science]. Phosphatases catalyze the hydrolytic removal of these phosphate groups, a process known as dephosphorylation [Tonks, 2006, Nat Rev Mol Cell Biol]. These opposing actions function as a molecular switch to regulate protein conformation, activity, localization, and stability within signaling cascades.