In biochemistry, a kinase is a type of enzyme that transfers phosphate groups from high-energy donor molecules, such as ATP, to specific target molecules (substrates); the process is termed phosphorylation. An enzyme that removes phosphate groups from targets is known as a phosphatase. Biochemistry is the study of the chemical processes and transformations in living organisms. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Above is a ball-and-stick model of the inorganic phosphate molecule (HPO42−). Colour coding: P (orange); O (red); H (white). ... Adenosine 5-triphosphate (ATP), discovered in 1929 by Karl Lohmann,[1] is a multifunctional nucleotide primarily known in biochemistry as the molecular currency of intracellular energy transfer. ... In biochemistry, a substrate is a molecule which is acted upon by an enzyme. ... Phosphorylation is the addition of a phosphate (PO4) group to a protein or a small molecule. ... A phosphatase is an enzyme that hydrolyses phosphoric acid monoesters into a phosphate ion and a molecule with a free hydroxyl group. ...

In some settings, the purpose of phosphorylation is to "activate" or "energize" a molecule, increasing its energy so it is able to participate in a subsequent reaction with a negative free-energy change. All kinases require a divalent metal ion such as Mg²⁺ or Mn²⁺ to be present, which stabilizes the high-energy bonds of the donor molecule (Usually ATP or ATP Derivative) and allows phosphorylation to occur. In thermodynamics, the Gibbs free energy is the energy portion of a thermodynamic system available to do work. ... Hot metal work from a blacksmith In chemistry, a metal (Greek: Metallon) is an element that readily forms positive ions (cations) and has metallic bonds. ... An ion is an atom or group of atoms that normally are electrically neutral and achieve their status as an ion by loss (or addition) of an electron(s). ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Atomic mass 24. ... General Name, Symbol, Number manganese, Mn, 25 Chemical series transition metals Group, Period, Block 7, 4, d Appearance silvery metallic Atomic mass 54. ...

In other instances, phosphorylation of a protein substrate can inhibit its activity (as when AKT phosphorylates the enzyme GSK-3). One common mechanism for phosphorylation-mediated enzyme inhibition was demonstrated in the tyrosine kinase called "src" (pronounced "sarc", see: Src (gene)). When src is phosphorylated on a particular tyrosine, it folds on itself, and thus masks its own kinase domain, and is thus shut "off". Akt, also known as protein kinase B (PKB) is an important molecule in mammalian cellular signaling. ... Glycogen Synthase Kinase 3 (GSK-3) is a serine/threonine protein kinase. ... Src is a family of proto-oncogenes that may lead to cancer. ...

In still other instances, phosphorylation of a protein causes it to be bound to other proteins which have "recognition domains" for a phosphorylated tyrosine, serine, or threonine motif. As a result of binding a particular protein, a distinct signaling system may be activated or inhibited. Tyrosine (from the Greek tyros, meaning cheese, as it was first discovered in cheese), 4-hydroxyphenylalanine, or 2-amino-3(4-hydroxyphenyl)-propanoic acid, is one of the 20 amino acids that are used by cells to synthesize proteins. ... Serine is one of the 20 natural amino acids. ... Threonine is one of the 20 natural amino acids. ...

In the late 1990s it was recognized that phosphorylation of some proteins causes them to be degraded by the ATP-dependent ubiquitin/proteasome pathway. These target proteins become substrates for particular E3 ubiquitin ligases only when they are phosphorylated. Ubiquitin is a small regulatory protein that is ubiquitous in eukaryotes. ... A proteasome is a barrel-shaped multi-protein complex that can digest other proteins into short polypeptides and amino acids in an ATP-driven reaction. ... Ubiquitin is a small regulatory protein that is ubiquitous in eukaryotes. ...

The largest group of kinases are Protein kinases, which act on and modify the activity of specific proteins. These are used extensively to transmit signals and control complex processes in cells. Various other kinases act on small molecules (lipids, carbohydrates, amino acids, nucleotides, and more), either for signaling or to prime them for biochemical reactions in metabolism. These are named after their substrates and include: A protein kinase is an enzyme that modifies other proteins by chemically adding phosphate groups to them (phosphorylation). ...

• Adenylate kinase
• Creatine kinase;
• Pyruvate kinase;
• Tyrosine kinase;
• Hexokinase;
• Nucleotide diphosphate kinase;
• Thymidine kinase.

Adenylate kinase (also known as ADK) is a phosphotransferase enzyme (EC 2. ... Creatine Kinase Creatine kinase (CK), also known as phosphocreatine kinase or creatine phosphokinase (CPK) is an enzyme (EC 2. ... Pyruvate kinase is an enzyme involved in glycolysis. ... Tyrosine kinases are a subclass of protein kinase, see there for the principles of protein phosphorylation A tyrosine kinase (EC 2. ... A hexokinase is an enzyme that phosphorylates a six-carbon sugar, a hexose, to a hexose phosphate. ... Thymidine kinase TK, is an enzyme, a phosphotransferase (a kinase): 2-deoxythymidine kinase, ATP-thymidine 5-phosphotransferase, {{{EC 2. ...

See Also

• CAMP-dependent protein kinase
• Protein kinase
• Signal transduction
• G protein-coupled receptor
• Serine/threonine-specific protein kinase
• Calmodulin dependent kinase
• Calmodulin kinase
• Extracellular signal-regulated kinases
• Class I PI 3-kinases
• Class II PI 3-kinases
• Phosphoinositide 3-kinase