phosphorylation

(redirected from phosphorylated)
Also found in: Dictionary, Medical.

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
..... Click the link for more information.
, 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
..... Click the link for more information.
 (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
..... Click the link for more information.
) 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.
References in periodicals archive ?
Under observation with highest magnification (100x objective lens), we found that tyrosine phosphorylated proteins are localized in both nucleus and cytoplasm of Sertoli cell as shown in Figure 2A as compared to that of control (Fig.
DAP in water at room temperature also phosphorylated the amino acids glycine, aspartic acid and glutamic acid, and then helped link these molecules into short peptide chains (peptides are smaller versions of proteins).
B activation in HK-2 cells, the mRNA and protein expression of upstream transmembrane receptor TLR4 and protein expression of phosphorylated ERK1/2, phosphorylated p38MAPK, and p-MEK1 were assayed in HK-2 cells.
i] per mol myosin (500 kDa), indicating that the myosin is phosphorylated at multiple sites (Fig.
Immunohistochemically, the tumor was strongly positive for CD34 (figure 4, A) and bcl-2 (figure 4, B), mildly positive for phosphorylated protein kinase B (pAKT) and phosphorylated extracellular signal-regulated kinase 1/2 (pERK 1/2), and negative for pan cytokeratin(AEl/AE3),EMA, platelet-derived growth factor receptor (PDGFR) alpha and p53.
The mechanism by which berberine modulates -germline transcript expression might be through regulating the phosphorylated IkBa level and the expressions of signal transducer and activator of transcription-3 and T-box transcription factor TBX21.
RPPA uses an avidin-biotin-based amplification step to achieve a sensitivity that can reach low-abundance phosphorylated signal pathway proteins with a detection sensitivity of less then a cell equivalent (2).
They underwent lumbar puncture to ascertain cerebrospinal fluid levels of beta-amyloid-42 (Abeta-42), total tau, and phosphorylated tau.
Specifically, FoxO1, a known target of Akt kinase activity (28), is phosphorylated and subsequently sequestered in the cytoplasm and kept removed from its nuclear target genes upon Akt activation (6,28,35).
Tau supplementation improved glucose tolerance and insulin sensitivity with a higher ratio of Akt phosphorylated (pAkt) related to Akt total protein content (pAkt/Akt) following insulin administration in the liver without altering body weight and fat deposition in HTAU mice.
The team showed that embryonal carcinoma cells with deregulated Akt activation and more phosphorylated Oct4 are more resistant to cell death signals such as ultraviolet irradiation and high glucose treatment.
Phosphorylated salivary proteins such as statherin are known to help enhance mineral delivery to the tooth surface and provide protection against dental caries.

Full browser ?