What is the relationship between kinases and phosphatases?

A kinase is an enzyme that attaches a phosphate group to a protein. A phosphatase is an enzyme that removes a phosphate group from a protein. Together, these two families of enzymes act to modulate the activities of the proteins in a cell, often in response to external stimuli.

What effect does kinase have on its substrate?

In biochemistry, a kinase is an enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates. This process is known as phosphorylation, where the high-energy ATP molecule donates a phosphate group to the substrate molecule.

What do kinases and phosphatases do?

Protein kinases and phosphatases are enzymes catalysing the transfer of phosphate between their substrates. A protein kinase catalyses the transfer of γ-phosphate from ATP (or GTP) to its protein substrates while a protein phosphatase catalyses the transfer of the phosphate from a phosphoprotein to a water molecule.

How are kinases and phosphatases involved in signal transduction?

The end effects of all four signal transduction systems are largely mediated by protein (serine/threonine) kinases and/or phosphatases. A family of four protein (serine/threonine) phosphatases account for dephosphorylation of all known cytosolic or nuclear substrates phosphorylated by these protein kinases.

What is the function of a kinase enzyme?

Protein kinases (PTKs) are enzymes that regulate the biological activity of proteins by phosphorylation of specific amino acids with ATP as the source of phosphate, thereby inducing a conformational change from an inactive to an active form of the protein.

How is substrate recruitment related to kinase specificity?

Substrate recruitment is any process that can bring a kinase and a substrate in close proximity, thus increasing the effective concentration of the substrate and increasing the chance of forming the enzyme–substrate complex.

What is the peptide specificity of a protein kinase?

The molecular recognition of the peptide sequence surrounding the phosphorylated residue of a substrate is usually referred to as the “peptide specificity” of a protein kinase.

How are phosphorylation sites assigned to protein kinases?

Although almost 2% of all proteins encoded in the human genome are protein kinases [3] and 30–50% of proteins have been estimated to be phosphorylated [4], only a small fraction of phosphorylation sites has been assigned thus far [5]. Defects in protein kinase function result in a variety of diseases and kinases are major targets for drug design.