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排序方式: 共有113条查询结果,搜索用时 31 毫秒
1.
Teresa K. Aman Bruce A. Maki Thomas J. Ruffino Eileen M. Kasperek Gabriela K. Popescu 《The Journal of biological chemistry》2014,289(27):18805-18817
Protein kinase A (PKA) enhances synaptic plasticity in the central nervous system by increasing NMDA receptor current amplitude and Ca2+ flux in an isoform-dependent yet poorly understood manner. PKA phosphorylates multiple residues on GluN1, GluN2A, and GluN2B subunits in vivo, but the functional significance of this multiplicity is unknown. We examined gating and permeation properties of recombinant NMDA receptor isoforms and of receptors with altered C-terminal domain (CTDs) prior to and after pharmacological inhibition of PKA. We found that PKA inhibition decreased GluN1/GluN2B but not GluN1/GluN2A gating; this effect was due to slower rates for receptor activation and resensitization and was mediated exclusively by the GluN2B CTD. In contrast, PKA inhibition reduced NMDA receptor-relative Ca2+ permeability (PCa/PNa) regardless of the GluN2 isoform and required the GluN1 CTD; this effect was due primarily to decreased unitary Ca2+ conductance, because neither Na+ conductance nor Ca2+-dependent block was altered substantially. Finally, we show that both the gating and permeation effects can be reproduced by changing the phosphorylation state of a single residue: GluN2B Ser-1166 and GluN1 Ser-897, respectively. We conclude that PKA effects on NMDA receptor gating and Ca2+ permeability rely on distinct phosphorylation sites located on the CTD of GluN2B and GluN1 subunits. This separate control of NMDA receptor properties by PKA may account for the specific effects of PKA on plasticity during synaptic development and may lead to drugs targeted to alter NMDA receptor gating or Ca2+ permeability. 相似文献
2.
Protein metabolism during endurance exercise 总被引:2,自引:0,他引:2
After reviewing all the available results from our laboratory and numerous reports in the literature concerning changes that have occurred in various aspects of protein metabolism during exercise, a number of conclusions can be drawn with some degree of confidence. During exercise, protein synthesis is depressed and this change leaves amino acids available for catabolic processes. The rate of leucine oxidation appears to be increased during exercise, and there is a movement of amino acids, mostly in the form of alanine, from muscle to liver where the rate of gluconeogenesis is increased as a result of exercise. These changes in protein metabolism are probably physiologically significant in at least three ways: amino acid conversion to citric acid cycle intermediates enhances the rate of oxidation of acetyl-CoA generated from glucose and fatty acid oxidation; increased conversion of amino acids to glucose helps to prevent hypoglycemia; oxidation of some amino acids may provide energy for muscular contraction. 相似文献
3.
On the mechanisms of ATP-induced and succinate-induced redistribution of cations in isolated rat liver cells 总被引:3,自引:0,他引:3
1. The ability of external ATP to induce calcium uptake in isolated rat liver cells was further characterized. Stimulation of calcium uptake was specific for ATP, other nucleotides or ATP metabolites had no comparable effect. ATP was dephosphorylated while stimulating calcium uptake, but there was no stoichiometry between ATP hydrolysis and calcium uptake nor did dephosphorylation depend on calcium concentration. ATP acted from outside and was dephosphorylated by an ecto-ATPase of the cells. 2. In addition to its direct action, ATP enhanced succinate-dependent calcium uptake in a cooperative fashion. This is best explained by different sites of action. ATP increases cell membrane permeability while succinate stimulates uptake into mitochondria. 3. ATP was able to lower Na+ and K+ gradients and the pH gradient between cells and incubation medium. Increasing calcium concentration counteracted this effect though calcium uptake was then stimulated. 4. Succinate alone did not affect monovalent cation gradients but raised the pH gradient. It partially counteracted the ATP effects on these gradients. 5. Since catecholamine-like actions of ATP may be mediated by an increase in cytoplasmic calcium concentration, the action of extracellular ATP can be taken as a model to study the role of calcium as a transmitter of hormone actions. From interdependence between ATP-stimulated and succinate-stimulated calcium uptake, conclusions can be drawn on the resulting cytoplasmic calcium concentration and its effect on plasma membrane permeability. 相似文献
4.
Ingrid Lombeck K. Kasperek L. E. Feinendegen H. J. Bremer 《Biological trace element research》1980,2(3):193-198
The rubidium content of whole blood was estimated by instrumental neutron activation analysis. In 46 healthy children it amounts
to {ie193-1} g/g dry weight. There was no difference between the values found for infants, toddlers, and school children.
In 29 dietetically treated patients with phenylketonuria and maple-syrup-urine disease the values were significantly lower
than in healthy children. During the first three months of diet therapy the rubidium levels remained in the lower range of
the normal values, decreasing to about 60% of the mean of normal values later on. With increasing length of diet therapy these
values tended to decrease. It remains questionable whether these decreased levels reflect only an induced biochemical phenomenon
without biological importance, or whether they are the first signs of a deficiency syndrome. 相似文献
5.
Several reports have shown that amino acid utilization via oxidation and gluconeogenesis is increased during exercise. The purpose of this study was to investigate whether these changes are accompanied by alterations in protein synthesis and degradation in the muscle of exercising rats. One group of rats was made in swim for 1h and then protein synthesis and protein degradation were measured in a perfused hemicorpus preparation. Protein synthesis was decreased and protein degradation was increased in exercised rats compared with sedentary control rats. Exercise also decreased amino acid incorporation by isolated polyribosomes from muscle. Measurement of several muscle proteinase activities demonstrated that exercise had no effect on alkaline proteinase or Ca2+-activated proteinase. However, the free (unbound) cathepsin D activity was elevated in muscle of exercised rats, whereas the total activity of catepsin D was unchanged. This increase in the proportion of free cathepsin D activity suggests that lysosomal enzymes may be involved in the increased protein degradation that was observed. 相似文献
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8.
Jessica AB van Nies Rute B Marques Stella Trompet Zuzana de Jong Fina AS Kurreeman Rene EM Toes J Wouter Jukema Tom WJ Huizinga Annette HM van der Helm-van Mil 《Arthritis research & therapy》2010,12(2):R38
Introduction
Recently an association between a genetic variation in TRAF1/C5 and mortality from sepsis or cancer was found in rheumatoid arthritis (RA). The most prevalent cause of death, cardiovascular disease, may have been missed in that study, since patients were enrolled at an advanced disease stage. Therefore, we used an inception cohort of RA patients to investigate the association between TRAF1/C5 and cardiovascular mortality, and replicate the findings on all-cause mortality. As TRAF1/C5 associated mortality may not be restricted to RA, we also studied a large cohort of non-RA patients. 相似文献9.
Intervention with mesenchymal stem cells (MSCs) represents a promising therapeutic tool in treatment-refractory autoimmune
diseases. A new report by Schurgers and colleagues in a previous issue of Arthritis Research & Therapy sheds novel mechanistic insight into the pathways employed by MSCs to suppress T-cell proliferation in vitro, but, at the same time, indicates that MSCs do not influence T-cell reactivity and the disease course in an in vivo arthritis model. Such discrepancies between the in vitro and in vivo effects of potent cellular immune modulators should spark further research and should be interpreted as a sign of caution
for the in vitro design of MSC-derived interventions in the setting of human autoimmune diseases. 相似文献
10.
Bahareh Honarparvar Sachin A Pawar Cláudio Nahum Alves Jer?nimo Lameira Glenn EM Maguire José Rogério A Silva Thavendran Govender Hendrik G Kruger 《Journal of biomedical science》2015,22(1)