phosphorylation


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phosphorylation,

chemical process in which a phosphate group is added to an organic molecule. In living cells phosphorylation is associated with respirationrespiration,
process by which an organism exchanges gases with its environment. The term now refers to the overall process by which oxygen is abstracted from air and is transported to the cells for the oxidation of organic molecules while carbon dioxide (CO2
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, which takes place in the cell's mitochondria, and photosynthesis, which takes place in the chloroplasts. The energy released during metabolic or photosynthetic processes is captured in the energy-rich phosphate bonds of certain molecules, most commonly in the high-energy bonds of adenosine triphosphateadenosine triphosphate
(ATP) , organic compound composed of adenine, the sugar ribose, and three phosphate groups. ATP serves as the major energy source within the cell to drive a number of biological processes such as photosynthesis, muscle contraction, and the synthesis of
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 (ATP). In the process of oxidative phosphorylation ATP formation is associated with respiratory uptake of oxygen. In this process a cell substance known as NADH (one of a variety of coenzymescoenzyme
, any one of a group of relatively small organic molecules required for the catalytic function of certain enzymes. A coenzyme may either be attached by covalent bonds to a particular enzyme or exist freely in solution, but in either case it participates intimately in
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) donates hydride ions (one proton and two electrons) to the first of a series of enzymes in the so-called electron transport chain. As the hydride ion is passed from one enzyme to another in the chain, energy is made available to power the formation of ATP from adenosine diphosphate (ADP) and inorganic phosphate. At the end, or lowest energy level, of the electron transport chain, the hydride ion combines with oxygen and a proton (hydrogen ion) to form a water molecule. The phosphorylation process is linked to cell metabolism in that metabolic degradation of food, e.g., glucose, allows formation of the coenzyme NADH. The electron transport enzymes are complex aggregates of cytochromes, i.e., proteins with iron-containing heme groups, and various coenzymes. The precise mechanisms by which chemical energy is coupled to ATP synthesis are not yet understood. In photosynthetic phosphorylation, or photophosphorylation, substances such as the reduced coenzyme NADPH also donate hydride ions to an electron transport system so that ATP is synthesized from ADP and inorganic phosphate; in photophosphorylation, however, the coenzyme is produced from chemical reactions initiated by illuminated photosynthetic pigments instead of from metabolism of food molecules. The net result in phosphorylation of ADP is the formation of the high-energy molecule ATP, which the cell can use as a kind of universal energy currency to power many important cell processes, such as protein synthesis. Other phosphorylation reactions occur in cells, some without mediation by the electron transport chain, e.g., ATP is formed from ADP and inorganic phosphate in a reaction coupled to the oxidation of glyceraldehyde phosphate to phosphoglyceric acid.

Phosphorylation

 

the replacement of a hydrogen atom in a molecule of a chemical compound by an acid residue of phosphorus, usually a residue of phosphoric acid. Primary and secondary amines, alcohols, mercaptans, and other nucleophilic compounds are the most readily phosphorylated. Hydrocarbons (radical mechanism) and alkyl halides (ion mechanism) can also be subjected to phosphorylation. The phosphorylating agents used are acids of phosphorus and the derivatives of these acids, usually acid halides and anhydrides and, less often, esters and amides. For example:

ROH + CIP(O)(OR’)2

→ ROP(O)(OR’)2 + HCI

3R2NH + PCI3 → P(NR2)3 + 3HCI

During phosphorylation, the acids of phosphorus usually act together with condensing agents, such as carbodiimides and sulfochlorides. The capacity for phosphorylation depends on the valence of phosphorus in the phosphorylating agent, with derivatives of phosphorus (III) having the highest reactivity. Phosphorylation is widely used in the synthesis of noncombustible materials and of plasticizers, extractants, pesticides, and pharmaceuticals.

Phosphorylation has an important metabolic role in animals, plants, and microorganisms. It is catalyzed by enzymes and occurs as a result of either phosphorolysis or phosphokinase-catalyzed reactions:

A—B + C—H2PO3→A—H2PO3 + B—C

where A—B is the molecule that accepts the phosphoryl group (acceptor), and C—H2PO3 is the molecule that gives up the phosphoryl group (donor). Donors of the phosphoryl group include molecules of adenosine triphosphate and other nucleoside triphosphates. During metabolism, various low-molecular-weight compounds, as well as proteins, are subjected to phosphorylation. The phosphorylation of adenosine diphosphate by inorganic phosphoric acid serves as a basic mechanism for the formation of adenosine triphosphate and the accumulation of energy necessary for biosynthesis, as well as for the mechanical, electrical, and osmotic activity of the cell; it is carried out by polyenzymatic systems as a result of oxidation reactions of low-molecular-weight organic compounds either in the absence of oxygen (glycolytic phosphorylation) or through the effect of oxygen (oxidative phosphorylation). The phosphorylation of adenosine diphosphate into adenosine triphosphate during photosynthesis is called photophosphorylation.

E. E. NIFANTEV and A. D. VINOGRADOV

phosphorylation

[‚fäs‚fȯr·ə′lā·shən]
(organic chemistry)
The esterification of compounds with phosphoric acid.
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K] are dependent not only on expression levels of the potassium channel, but also on the phosphorylation status of the channels (25).
Furthermore, our results suggest that this association is regulated through the tyrosine phosphorylation of the Claudin-3 C-terminus.
01) the marein-induced elevation of AMPK phosphorylation at threonine 172 (Fig.
Unlike other modifications which stem from changes to the RUNX3 DNA itself or how DNA is read, phosphorylation does not accompany any changes in the DNA and is hence undetectable at the genetic level.
To monitor ATM activation, we examined the phosphorylation status of three well-characterized ATM targets: ATM autophosphorylation at Ser1981, CHK2 at Thr68, and transcription/chromatin regulator KAP1 at Ser824 (Shiloh and Ziv 2013).
Stimulation of H295R cells with Ang II for 5 min caused a dose-dependent phosphorylation of ERK1/2, with the maximum effect occurring at the concentration of 100 nM and 1000 nM (Figure 1).
To understand how formononetin induces the phosphorylation of GSK-3[beta] at Ser9, following OGD/reoxygenation challenge, we treated the cells with formononetin in combination with PI3K inhibitor LY294002 (LY), PKC inhibitor GF109203X (GF), and ERK 1/2 inhibitor PD98059 (PD).
The aim of this study was to investigate p70S6K phosphorylation in peripheral blood mononuclear cells (PBMCs) of liver transplant patients who received different immunosuppressive drug regimens with or without sirolimus by phospho-flow cytometry and Western blotting.
AlphaLISA SureFire Ultrasensitivity and dynamic range also make the assays suitable for other screening types, including small molecule modulation, detection of low and basal levels of phosphorylation, and detection of phosphorylation in tissue lysates.
Regarding mechanism of action of NF-B its phosphorylation is necessary at Serine 276 site of p65subunit[4].
4,10,11) Moreover, it has been also shown that XRCC4 undergoes phosphorylation in living cells in response to radiation or treatment with DSB-inducing agent in a manner dependent on DNA-PKcs.
Phosphorylation of certain serine at ER may relate to breast cancer process and on-going treatment.

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