Transphosphorylation


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Transphosphorylation

 

the enzymatic transfer of a phosphoric acid residue (phosphategroup, —PO32–) from one compound to another in living cells. Transphosphorylation links the most important reactions of metabolism in the cell, carrying out an exchange of energy between various processes by forming and breaking energy-rich phosphate bonds. In the majority of transphosphorylation reactions, the phosphate is transferred to the hydroxyl group of an alcohol or carbohydrate, with the formation of an energy-poor bond. A molecule of adenosine triphosphate (ATP) usually serves as the donor of the phosphategroup. The transphosphorylation reaction is catalyzed by phosphotransferase enzymes, which usually require the presence of Mg2+ to become active.

References in periodicals archive ?
The HER2 protein is analogous to other receptor tyrosine kinases: it is expressed at the cell surface; it exists there in homodimeric form, as well as in heterodimers with other ErbB family members; and it possesses intracellular domains capable of transphosphorylation and interaction with downstream effectors.
Thus, smaller than 1 ratios of Pi / p-nitrophenol and greater ratios of phosphate transfer to hydrolysis showed the presence of transphosphorylation reaction.
Cr and PCr are in rapid exchange via the reversible transphosphorylation reaction catalyzed by enzyme creatine kinase (CK) (Wyss and Kaddurah-Daouk 2000).
We next examined the potential of EGFR activation through transphosphorylation by a kinase intermediate.
Alcohols such as methanol ethanol and glycerol at concentrations of 10 % showed no activating effect on the activity suggesting that acid phosphatase was not involved in the transphosphorylation reaction.
As a general rule, ligand binding promotes the formation of homo and heterodimers between different receptors, which leads to the activation of the cytoplasmic domain kinase activity, resulting in transphosphorylation of the latter in tyrosine residues [1].
Sequential transphosphorylation of the BRI1/BAKI receptor kinase complex impacts early events in brassinosteroid signaling.
Using site-directed mutagenesis, nine cysteine residues (675, 722, 748, 787, 866, 917, 961, 1094, and 1105), within JAK2 were individually and progressively mutated to serines and the effects of these mutations were tested in autophosphorylation and transphosphorylation assays.