Substrate Phosphorylation

Substrate Phosphorylation

 

in biochemistry, the synthesis of energy-rich phosphorus compounds using the energy of the oxidation-reduction reactions of glycolysis, which are catalyzed by phosphoglyceraldehyde dehydrogenase and enolase. It also takes place upon oxidation of α-ketoglutaric acid in the Krebs cycle (under the action of a-ketoglutarate dehydrogenase and succinate thiokinase). For bacteria, cases of substrate phosphorylation upon oxidation of pyruvic acid have been described.

Substrate phosphorylation, in contrast to phosphorylation in an electron transport system (seeOXIDATIVE PHOSPHORYLATION), is not inhibited by general poisons, such as dinitrophenol, and is not related to the fixation of enzymes in mitochondrial membranes. The contribution of substrate phosphorylation to the cellular supply of adenosine triphosphate under aerobic conditions is significantly less than the contribution of phosphorylation in an electron transport system.

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Because LTP is promoted by strong stimuli versus weak for LTD, one plausible explanation is that graded levels of CaMKII activity and/or autophosphorylation promote differential substrate phosphorylation to induce the opposing forms of synaptic plasticity.
Conceptually, one might expect that a similar number of activated [T.sup.287] autophosphorylated subunits ([T.sup.286] in alpha isoform) would produce similar levels of substrate phosphorylation within the PSD regardless of whether the catalytic subunits are within a holoenzyme or monomeric.
Thus, while the enzymatic activity of monomeric CaMKII is favored or equal (start or end of the reaction) to that of the holoenzyme CaMKII, substrate phosphorylation is higher for CaMKII when multiple subunits are activated within the holoenzyme for a diffusion-restricted environment like the PSD.
Specific degradation of troponin T and I by mu-calpain and its modulation by substrate phosphorylation. Biochem J 1995;308:57-61.
GSK-3-dependent substrate phosphorylation may represent a signal toward their degradation.
Fifthly, it has been reported that local regulation of cAMP and substrate phosphorylation play important roles in [beta]-adrenergic receptor signaling [26, 36-38], so it could be useful to incorporate local control mechanism in a future study.
In order to elucidate the ostensibly contradictory findings of MEK1 /2 hyperphosphorylation and decrease in substrate phosphorylation, the influence of 7-epi-nemorosone on the kinase activity of MEK1 /2 was studied in a cell-free system.
Therefore, similar allosteric regulation of substrate phosphorylation may have a more general meaning and play a significant role in various 'decision-making' steps of the cell cycle.
Briefly, the initial velocities of substrate phosphorylation reaction (v) were measured at various ATP (A) and peptide (B) concentrations.
Since these enzymes target tyrosine sites rather than ser/thr sites, it is unlikely that they directly affect substrate phosphorylation, but they may have some alternative regulatory role that affects the activity of proline-directed kinases such as cdc2, cdk5, and Erk1/2.
Insulin-receptor autophosphorylation and endogenous substrate phosphorylation in human adipocytes from control, obese, and NIDDM subjects.