kinase


kinase
/kuy"nays, -nayz, kin"ays, -ayz/, n. Biochem.
a transferase that catalyzes the phosphorylation of a substrate by ATP.
[1900-05; KIN(ETIC) + -ASE]

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enzyme
 an enzyme that adds phosphate groups (PO43−) to other molecules. A large number of kinases exist—the human genome contains at least 500 kinase-encoding genes (gene). Included among these enzymes' targets for phosphate group addition ( phosphorylation) are proteins (protein), lipids (lipid), and nucleic acids (nucleic acid).

      For protein targets, kinases can phosphorylate the amino acids serine, threonine, and tyrosine. The reversible phosphorylation of proteins, by the antagonistic (opposing) action of kinases and phosphatases, is an important component of cell signaling because the phosphorylated and unphosphorylated states of the target protein can have different levels of activity. Edwin Gerhard Krebs (Krebs, Edwin Gerhard) and Edmond H. Fischer (Fischer, Edmond H.) received the Nobel Prize for Physiology or Medicine in 1992 for their work in establishing this paradigm.

      Phosphorylation of lipid molecules by kinases is important for controlling the molecular composition of membranes (membrane) in cells, which helps to specify the physical and chemical properties of the different membranes. inositol, a compound similar in structure to a carbohydrate, is phosphorylated by kinases to create a diverse array of phosphoinositol and phosphoinositide lipids. These molecules then function as second messengers (second messenger) to propagate signaling information throughout the cell.

      Nucleotides (nucleotide), the fundamental units of RNA (ribonucleic acid) and DNA (deoxyribonucleic acid), contain a phosphate molecule attached to a nucleoside, a compound made up of a ribose moiety and a purine or pyrimidine base. In polymers (polymer) of RNA and DNA, the backbone is composed of repeating phospho-ribose units. Kinases attach the phosphate to the nucleoside, creating a nucleotide monophosphate. For example, an enzyme called nucleoside phosphorylase serves this role when cells switch to synthesizing nucleotides from recycled purines instead of from new starting materials. Mutations (mutation) in the gene encoding nucleoside phosphorylase can cause a severe form of immune deficiency.

       metabolism of dietary sugars (glycolysis) involves several different steps of phosphorylation by distinct kinases. These phosphate groups are ultimately used to form the high-energy compound known as ATP ( adenosine triphosphate).

      Inhibitors of kinases can be important treatments for human diseases in which hyperactive processes need to be dampened. For example, one form of human leukemia, CML (chronic myelogenous leukemia), is caused by excess activity of the Abelson tyrosine kinase. Imatinib (Gleevec) is a chemical that binds to the active site of this kinase, thereby blocking the enzyme's ability to phosphorylate targets. Imatinib has been useful in the initial treatment of CML; however, in many cases the kinase enzyme mutates, rendering the drug ineffective.

John A. Cooper
 

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Universalium. 2010.

Look at other dictionaries:

  • kinase — [ kinaz ] n. f. • 1902; du gr. kinein « mettre en mouvement » et ase ♦ Biochim. Enzyme capable d activer par phosphorylation un métabolite, un autre enzyme (phosphorylase kinase) ou une protéine impliquée dans la réponse cellulaire à certains… …   Encyclopédie Universelle

  • Kinase — Enzymklassifikation EC, Kategorie …   Deutsch Wikipedia

  • kinase — ki nase (k[imac] n[=a]s), n. (Biochemistry) One of a class of enzymes that catalyze transfer of a phosphate group from ATP to another molecule; it is a type of phosphorylase. [PJC] …   The Collaborative International Dictionary of English

  • kinase — 1902, from Gk. kinein to move (see CITE (Cf. cite)) + chemical suffix ASE (Cf. ase) …   Etymology dictionary

  • kinase — [kī′nās΄, kin′ās΄] n. [ KIN(ETIC) + ASE] an enzyme capable of activating a zymogen or one causing the transfer of the terminal phosphate group, generally from ATP, to a receiving molecule …   English World dictionary

  • Kinase — Les kinases, appelées à tort phosphorylases[1] (catalyseur de la phosphorolyse), sont des enzymes du groupe des transférases catalysant les réactions de phosphorylation par l ajout d un ion phosphate à une molécule cible. La molécule cible,… …   Wikipédia en Français

  • Kinase — In chemistry and biochemistry, a kinase, alternatively known as a phosphotransferase, 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… …   Wikipedia

  • kinase — Widely used abbreviation for phosphokinase, an enzyme catalysing transfer of phosphate from ATP to a second substrate usually specified in less abbreviated name, eg. creatine phosphokinase (creatine kinase), protein kinase. Serine/threonine… …   Dictionary of molecular biology

  • kinase — noun Etymology: International Scientific Vocabulary, from kinetic Date: 1947 any of various enzymes that catalyze the transfer of phosphate groups from a high energy phosphate containing molecule (as ATP) to a substrate compare protein kinase …   New Collegiate Dictionary

  • kinase — 1. An enzyme catalyzing the conversion of a proenzyme to an active enzyme; e.g., enteropeptidase (enterokinase). 2. An enzyme catalyzing the transfer of phosphate groups. For individual kinases, see specific name. * * * ki·nase …   Medical dictionary


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