Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To determine the effect of starvation on brain insulin receptors, rats were fed 4 g of chow/day for 14 days and then P2 fraction membranes were prepared from different brain regions. Compared to the fed state, there was an 18% reduction of insulin binding in olfactory bulbs from starved animals, but no change in the cerebellum, frontal cortex, amygdala, medial hypothalamus or lateral hypothalamus. A 15% reduction of olfactory bulb insulin binding was obtained by totally starving animals for four days. When membrane content was measured using the plasma membrane marker Na/K ATPase, insulin binding decreased by 26% and 14% in olfactory bulb membranes from starved and totally starved animals, respectively. The starvation-induced change in olfactory bulb binding was due to a loss of binding sites and not a decrease in binding affinity. Non-specific catabolism of protein and a change in the composition of membranes following starvation were excluded as causes for this effect. As streptozotocin induced diabetes had no effect on brain insulin binding, it was concluded that hypoinsulinaemia associated with starvation had not caused the reduction in olfactory bulb binding. Under similar conditions of starvation and diabetes, insulin binding in liver plasma membranes increased 26% and 38%, respectively. At 8 and 14 days of starvation, the reductions in olfactory bulb insulin binding and body weight were similar. On refeeding for three days, there was no increase in insulin binding, although body weight increased 7%. On refeeding for eight days, olfactory bulb insulin and body weight had returned to near normal.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of starvation on insulin receptors in rat brain. 274 26

The intracellular level of DNA topoisomerase II appears to be reversibly regulated by serum concentration in cultured primary human skin fibroblasts (HSF). Upon serum starvation, the intracellular level of topoisomerase II in HSF, as monitored by immunoblotting with antitopoisomerase II antibodies, gradually decreased to a nondetectable level (less than 10(4) copies/cell) over a period of 72 h. Addition of 10% serum to the starved cells led to a gradual increase of the intracellular topoisomerase II to the original level (approximately 10(6) copies/cell) over a period of 24 h. The intracellular DNA topoisomerase II level in HSF is also sensitive to cell density; minimally a 7-fold decrease was observed when HSF were grown to saturation density in a constant serum concentration. Similarly, the intracellular levels of DNA topoisomerase II in other "nontransformed" cells such as mouse NIH 3T3 and 3T6 cells are also sensitive to both the serum concentration and the cell density. In contrast, topoisomerase II levels in transformed cells such as HeLa cells, L1210 cells, and SV40 T-antigen-transformed COS-1 cells are maintained at high levels (approximately 10(6) copies/cell) and are much less sensitive to growth conditions. The topoisomerase II level in HeLa cells synchronized by a double thymidine block remained relatively constant (less than 2-fold difference) throughout the late G1, S, G2, and M phases of the cell cycle. Our results suggest that the level of DNA topoisomerase II is primarily regulated in the G0-G1 phase of the cell cycle and is elevated to a high level (approximately 10(6) copies/cell) in proliferating cells. In contrast, the intracellular levels of DNA topoisomerase I in these cells were largely unaffected by these growth conditions either in HSF or in HeLa cells.
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PMID:Proliferation-dependent regulation of DNA topoisomerase II in cultured human cells. 283 57

The effects of starvation, feeding, and time of day on mouse gastric glands were studied by means of an enzyme histochemical method for K+-dependent p-nitrophenyl phosphatase (K+-NPPase), a partial reaction of the proton pump ATPase which drives gastric acid secretion. The stomachs of mice starved for 24 h showed very low levels of parietal cell K+-NPPase histochemical reaction. However, a brief meal following such a period of starvation produced an abrupt increase in K+-NPPase reaction within most of the parietal cell-containing glands though not all parietal cells were equally susceptible to stimulation. The number of glands containing K+-NPPase-reactive parietal cells fell slowly in the hours following a feeding stimulus. These changes were shown to be caused by feeding rather than by general arousal and to follow the feeding cycle in ad libitum fed animals. The reasons that parietal cells in the basal parts of mouse gastric glands cannot be induced to show K+-NPPase reactivity by a feeding stimulus are not understood.
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PMID:Effects of starvation, feeding, and time of day on the activity of proton transport adenosine triphosphatase in the parietal cells of the mouse gastric glands. 284 92

A single-gene nuclear mutant has been selected from the yeast Schizosaccharomyces pombe for growth resistance to Dio-9, a plasma membrane H+-ATPase inhibitor. From this mutant, called pma1, an ATPase activity has been purified. It contains a Mr = 100,000 major polypeptide which is phosphorylated by [gamma-32P] ATP. Proton pumping is not impaired since the isolated mutant ATPase is able, in reconstituted proteoliposomes, to quench the fluorescence of the delta pH probe 9-amino-6-chloro-2-methoxy acridine. The isolated mutant ATPase is sensitive to Dio-9 as well as to seven other plasma membrane H+-ATPase inhibitors. The mutant H+-ATPase activity tested in vitro is, however, insensitive to vanadate. Its Km for MgATP is modified and its ATPase specific activity is decreased. The pma1 mutation decreases the rate of extracellular acidification induced by glucose when cells are incubated at pH 4.5 under nongrowing conditions. During growth, the intracellular mutant pH is more acid than the wild type one. The derepression by ammonia starvation of methionine transport is decreased in the mutant. The growth rate of pma1 mutants is reduced in minimal medium compared to rich medium, especially when combined to an auxotrophic mutation. It is concluded that the H+-ATPase activity from yeast plasma membranes controls the intracellular pH as well as the derepression of amino acid, purine, and pyrimidine uptakes. The pma1 mutation modifies several transport properties of the cells including those responsible for the uptake of Dio-9 and other inhibitors (Ulaszewski, S., Coddington, A., and Goffeau, A. (1986) Curr. Genet. 10, 359-364).
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PMID:A single mutation confers vanadate resistance to the plasma membrane H+-ATPase from the yeast Schizosaccharomyces pombe. 287 25

The myofibrillar ATPase activity of the epaxial white muscle was measured in carp Cyprinus carpio L. acclimated to 10 degrees C or 28 degrees C. As previously reported, cold acclimation was associated with an increase in the ATPase specific activity and a decrease in the thermostability. The water content of the white muscle was significantly higher in cold-acclimated fish than in warm-acclimated fish (P less than 0.002). Starvation for 10 weeks resulted in a significant increase in the white muscle water content of both warm- and cold-acclimated fish (P less than 0.002). When carp were starved, the ability of the myofibrillar ATPase to show thermal compensation disappeared. Previously acclimated fish, when starved, showed steady alterations of the myofibrillar ATPase activity to a level mid-way between the acclimated extremes. Refeeding resulted in a gradual return to the normal acclimated level.
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PMID:Myofibrillar ATPase activity in the carp Cyprinus carpio: interactions between starvation and environmental temperature. 294 51

Oxygen consumption and Na+,K+-ATPase(EC 3.6.1.3)-dependent (ouabain-sensitive) and -independent respiration were measured for duodenal mucosa biopsies from 10-month-old sheep given two levels of digestible energy (DE) intake (7.6-7.7 and 14.8 MJ lucerne (Medicago sativa) pellets/d) and following 48 h of starvation. The mucosal biopsies were determined to be structurally intact and free of adherent bacteria on histological and scanning-electron-microscope examinations. The use of D-glucose as a substrate during incubations did not elevate (P greater than 0.05) the respiration indices of the biopsies over those measured during acetate incubations. Glucose uptake did not (P greater than 0.05) influence the Na+,K+-ATPase-dependent respiration of the mucosal biopsies. Na+,K+-ATPase-dependent respiration accounted for 50% of the total O2 consumption of the mucosal biopsies of sheep given the lower level of DE. Total O2 consumption of the duodenal mucosa was not (P greater than 0.05) increased when sheep were given the higher level of DE but Na+,K+-ATPase-dependent respiration of the mucosa was elevated (P less than 0.01) by 37% during this period. When sheep were starved for 48 h, total O2 consumption of the mucosal biopsies was not (P greater than 0.05) affected, however, Na+,K+-ATPase-dependent respiration of the biopsies dropped (P less than 0.01) by 45%. Na+,K+-ATPase-dependent respiration accounted for 61.3% of the O2 uptakes of mucosa from the sheep given the higher level of DE and 28.3% of the O2 uptake of mucosa from fasted sheep.
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PMID:Influence of feed intake and starvation on the magnitude of Na+,K+-ATPase(EC 3.6.1.3)-dependent respiration in duodenal mucosa of sheep. 299 48

Amino acid transport was studied in C1 cells which contain amplified levels of sodium- and potassium-activated adenosine triphosphatase (Na,K-ATPase), in C4 cells which are ouabain-sensitive revertants, and in parental HeLa S3. Sodium-dependent uptake of aminoisobutyric acid and alanine was increased 2-fold in the amplified C1 cells. After a 6 h amino acid starvation period, the rate of sodium-dependent uptake of methylaminoisobutyric acid was 70-90% greater for C1 than for C4 and HeLa. This uptake was inhibitable by ouabain and the apparent Km values for high affinity uptake were similar in all three lines. Overall, neutral amino acid uptake through Systems A, ASC, and L was 2-fold higher in the Na,K-ATPase amplified C1 cells relative to C4 or HeLa. The induction of System A uptake of methylaminoisobutyric acid after starvation was more rapid in both the amplified C1 cells and the revertant C4 when compared to HeLa, which suggests that the selection for amplification of the Na,K-ATPase produced membrane alterations affecting the adaptive regulation of System A.
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PMID:Alterations in amino acid transport in Na,K-ATPase amplified HeLa cells. 300 Oct 56

The effect of Ep on different ATPases and acetylcholinesterase of rat RBC membrane was studied. Starvation caused a slight decrease in Mg2+-, Ca2+-, and Na+ + K+-ATPases. However, these enzyme activities were markedly increased on Ep treatment of starved rats. Specific activities of all three ATPases increased linearly with increasing concentration of Ep. Under identical conditions the hormone failed to stimulate the ATPase activity of liver plasma membrane. Desensitization by fluoride of allosteric inhibition of erythrocyte membrane-bound Na+ + K+-ATPase was observed under starvation which showed a return to normal n values on Ep administration. The enzyme from normal animals was inhibited almost completely at 0.1 mM fluoride whereas enzyme from starved and Ep-treated animals showed only about 50% inhibition at that fluoride concentration. Ep increased the acetylcholinesterase activity of normal RBC membrane to a small extent whereas the stimulation was much higher under starvation. The fluoride inhibition curve of this enzyme changed from sigmoidal to hyperbolic under starvation which again changed to allosteric on administration of Ep. These changes were closely correlated to n values. Red blood cells of Ep-treated animals became more susceptible to osmotic shock under the experimental conditions.
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PMID:Effect of erythropoietin on the different ATPases and acetylcholinesterase of rat RBC membrane. 302 76

Sindbis virus infection of baby hamster kidney cells or chick embryo cells resulted in a significant increase in the rate of uptake of [2-3H]deoxy-D-glucose ([3H]dGlu). Stimulation of hexose transport in Sindbis virus-infected cells occurred only if the cells were rendered quiescent by culturing at high density or by serum starvation. In contrast, Sindbis virus-induced inhibition of potassium transport, measured as a decrease in the uptake of 86Rb+, was independent of cell growth state. Stimulation of [3H]dGlu uptake in Sindbis virus-infected cells was the result of an increase in the Vmax of the hexose transporter, but not a change in the Km. The stimulation of [3H]dGlu uptake induced by Sindbis virus was insensitive to the drug actinomycin D, but was blocked by cordycepin. The stimulation was also insensitive to treatment with tunicamycin, which prevented the virally induced inhibition of the plasma membrane-associated Na+/K+ ATPase and termination of host protein synthesis.
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PMID:Sindbis virus infection increases hexose transport in quiescent cells. 302 95

The ATP-binding component (Component II, hereafter referred to as ClpA) of a two-component, ATP-dependent protease from Escherichia coli has been purified to homogeneity. ClpA is a protein with subunit Mr 81,000. It has an intrinsic ATPase activity and activates degradation of protein substrates only in the presence of a second component (Component I, hereafter referred to as ClpP), Mg2+, and ATP. The amount of ClpA varies by less than a factor of 2 in cells grown in different media and at temperatures from 30 to 42 degrees C. ClpA does not appear to be a heat-shock protein since its synthesis is not dependent on htpR. Antibodies against purified ClpA were used to identify lambda transducing phage bearing the clpA gene. The cloned gene contains a DNA sequence expected to code for the first 28 amino acids of ClpA, which were determined by protein sequencing of purified ClpA. The clpA gene in the phage was mutated by insertion of delta kan defective transposons and the mutations were transferred to E. coli by homologous recombination. The clpA gene was mapped to 19 min on the E. coli chromosome. Mutant cells with insertions early in the gene produce no ClpA protein detectable in Western blots, and extracts of such mutant cells have no detectable ClpA activity. clpA- mutants grow well under all conditions tested and are not defective in turnover of proteins during nitrogen starvation nor in the turnover of such highly unstable proteins as the lambda proteins O, N, and cII, or the E. coli proteins SulA, RcsA, and glutamate dehydrogenase. The degradation of abnormal canavanine-containing proteins is defective in clpA mutants especially in cells that also have a lon- mutation. Extracts of clpA- lon- cells have ATP-dependent casein degrading activity.
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PMID:The two-component, ATP-dependent Clp protease of Escherichia coli. Purification, cloning, and mutational analysis of the ATP-binding component. 304 6


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