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

---

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

We tested the hypothesis that membrane vesicles of smooth muscle function as organelles controlling cell volume through a mechanochemical mechanism not involving Na+-K+ dependent membrane ATPase. Pieces of rat myometrium were incubated under various conditions at 25 degrees C, and then were analyzed after various times for Na+, K+, ATP and water contents or were prepared and examined in the electron microscope. Metabolic inhibition with iodoacetate (IAA) + dinitrophenol (DNP) rapidly depleted ATP, then decreased membrane vesicle number and increased vesicle size. Thereafter K+ loss, Na+ gain and water gain occurred. Slower depletion of ATP by treatment of tissues with IAA or ethacrynic acid produced similar, but delayed effects. Treatment with DNP alone, DNP in glucose-free Krebs-Ringer or glucose-free solution bubbled with N2 partly depleted the tissues of ATP but did not markedly affect the membrane vesicles or tissue water content. Ouabain affected neither ATP contents of tissues nor the numberof membrane vesicles, but produced large intracellular vesicles. The membrane vesicles were suggested to be sites of a mechanochemical volume control system.
...
PMID:Relation of membrane vesicles to volume and Na+ transport in smooth muscle: effect of metabolic and transport inhibition on fresh tissues. 15 83

In order to obtain information about the target of membrane-active inhibitors of platelet aggregation two phenylalkanoles and two phenylalkylamines were examined with respect to their influence on membrane ATPase and energy metabolism. The phenylalkanoles, 2-phenylethanol and 3-phenylpropanol, strongly enhanced the liberation in washed platelets of inorganic phosphate (Pi) from endogenous substrate or added ATP. A simultaneous decrease was found in the ATP/ADP ratio while glucose uptake, glycogen utilization and lactate formation increased. The effects of 2-phenylethanol and 3-phenylpropanol on Pi liberation and ATP/ADP ratio were detectable only with starving platelets; the stimulation of glycolysis could also be seen when glucose was added. It is concluded that presence of glucose enabled the platelets to reincorporate additionally liberated Pi into their ATP pool by virtue of the higher metabolic rate. The data suggest that a membrane-ATPase, possibly thrombosthenin ATPase, is the target of the phenylalkanoles. The phenylalkylamines, 2-phenylethylamine and 4-phenylbutylamine, appeared to inhibit Pi liberation and energy metabolism. Hence the aggregation inhibition produced by amphiphilic phenylalkylamines and phenylalkanoles is not due to a uniform metabolic effect of both classes of derivatives.
...
PMID:The effect of amphiphilic phenylalkyl derivatives on platelet energy metabolism. Stimulation of glycolysis through activation of membrane ATPase. 15 41

Ca2+ uptake into Ehrlich ascites tumor cells was studied at 0 degrees C in the presence of mitochondrial inhibitors, conditions that minimized complications caused by sequestration of Ca2+ into organelles or by excretion. Under these conditions Ruthenium Red inhibited Ca2+ uptake, but other previously implicated ions, such as Pi or Mg2+, had no effect. Valinomycin either inhibited or slightly stimulated Ca2+ uptake depending on the presence of excess K+ on the outside or inside of the cell, respectively. Nigericin inhibited Ca2+ transport. Based on these data we propose an electrogenic uptake of Ca2+, possibly via a Ca2+/H+ antiport mechanism. The observation that glucose inhibited Ca2+ uptake suggested that in Ehrlich ascites tumor cells an energy-driven Ca2+ expulsion mechanism is operative, similar to that in erythrocytes. Plasma membrane preparations of ascites tumor cells were found to contain a Ca2+-dependent ATPase. These preparations, when incorporated into liposomes in an inside-out orientation, catalyzed an ATP-dependent uptake of Ca2+.
...
PMID:Ca2+ translocation in Ehrlich ascites tumor cells. 15 90

The effects of glucose and oxygen on the formation of the plasma membrane of Staphylococcus aureus were studied. Phospholipids were consistent components of the membrane and were not affected by glucose or oxygen. Phospholipid fatty acids in cells grown in glucose containing media were rich in Ceven (C18, C20) fatty acid chains, whereas cells grown in glucose deficient media (normal broth) had anteiso Codd (C15,C17) fatty acid chains in place of Ceven chains. This may indicate increased membrane rigidity of the cells grown in glucose containing media. Cytochromes and ATPase were present in the membrane from cells grown in normal broth, but were deficient in the cells grown in glucose containing media. Polypeptide analysis of the membrane proteins showed a deficiency of the bands corresponding to these enzymes. They were not induced by the additionof oxygen to cells grown in glucose containing media. It was concluded that glucose was the dominant factor inhibiting the formation of these membrane enzymes.
...
PMID:Effect of glucose and oxygen on the structure of the plasma membrane of Staphylococcus aureus. 16 Jan 85

In conditions of glucose starvation, the maximum velocity of the mediated transport of nonmetabolized and metabolized amino acids, uridine, adenosine, and sucrose across the plasma membrane is stimulated by a factor of two by the addition of 1 mM adenosine 3':5'-monophosphate to Schizosaccharomyces pombe 972h- wild strain, to the glucose-super-repressed and derepressed mutants COB5 and COB6, and to Saccharomyces cerevisiae strain IL 216-IA. The mediated uptake of 2-D-deoxyglucose and the apparently nonmediated uptake of guanosine are not stimulated by the cyclic nucleotide. N6,O2'-Dibutyryl adenosine 3':5'-monophosphate is also efficient, whereas theophylline, guanosine 3':5'-monophosphate, 5'-AMP, ATP, and adenosine are ineffective. The cellular ATP content of glycerol-grown S. pombe COB5 is about 10 nmol per mg of protein and is not decreased by further incubation in the starvation medium. The addition of 100 mM glucose markedly enhances transport without any increase of the cellular ATP content. The addition of antimycin A or Dio-9 decreases markedly both cellular ATP content and transport. The addition of 2.5 mM glucose to antimycin A-containing medium restores both transport is not necessarily of mitochondrial origin. The uptake of 2-D-deoxyglucose is unaffected by the respiratory inhibitors. Stimulation of uptake by cyclic adenosine 3':5'-monophosphate occurs only in glucose-deprived cells. The addition of 10 mM glucose elicits the disappearance of the stimulation and prevents the 30% decrease of the cellular adenosine 3':5'-monophosphate content produced by glucose starvation. Adenosine 3':5'-'monophosphate does not enhance the steady state ATP level but requires cellular ATP produced either by endogenous respiration or, in the absence of respiration blocked by antimycin A, by further addition of 2.5 mM glucose. Stimulation of active uptake by adenosine 3':5'-monophosphate does not require protein synthesis because the addition of cycloheximide or anisomycin does not prevent the stimulation of L-leucine uptake. In the absence of respiration, Dio-9, and ATPase inhibitor, suppresses instantaneously the cellular ejection of protons as well as the uptake of uridine and amino acids. It abolishes also the adenosine 3':5'-monophosphate-stimulated transport. In the presence of antimycin A, specific mitochondrial ATPase inhibitors such as venruricidin A do not inhibit metabolite uptakes and their stimulation by adenosine 3':5'-monophosphate. These results suggest that in these conditions, the target of Dio-9 is not the mitochondrial ATPase but a plasma membrane proton-translocating function generating an electrochemical gradient required for active transport. That adenosine 3':5'-monophosphate enhances the Dio-9-sensitive proton extrusion supports the view that the cyclic nucleotide might modulate the plasma membrane ATPase.
...
PMID:Stimulation of active uptake of nucleosides and amino acids by cyclic adenosine 3' :5'-monophosphate in the yeast Schizosaccharomyces pombe. 16 26

Mitochondria from a rat mammary tumor (R3230AC) have been compared with mitochondria from pregnant and lactating rat mammary glands, with particular attention paid to inner membrane enzymes and Transport proteins. In the tumor the mitochondrial adenosine triphosphatase was not activated by 2,4-dinitrophenol, in contrast to the mammary mitochondria from lactating or pregnant rats. Translocation of adenosine diphosphate across the inner membrane was found to be more rapid in the tumor by virtue of lovered Km adenosine diphosphate and raised Vmax. Transport of phosphate and dicarboxylic acids occurred at similar rates in all three types of mitochondria. The inner membrane proteins were also examined directly by sodium dodecyl sulfate/polyacrylamide gel electrophoresis and some differences are noted. These results, although they indicate subtle differences between the inner mitochondrial membranes of tumor as compared with those of pregnant or lactating rat mammary glands, cannot form the basis of an explanation for enhanced glucose utilization and aerobic lactic acid production in this tumor.
...
PMID:A comparative study of inner membrane enzymes and transport systems in mitochondria from R3230AC mammary tumor and normal rat mammary gland. 16 45

Changes in the adenine nucleotide metabolism after an oral glucose load were studied in the liver of normal and alloxan-diabetic rats. Changes in the energy charge were positively correlated with those in the blood glucose and plasma immunoreactive insulin levels. One hour after an oral glucose load when the plasma immunoreactive insulin levels increased maximally, the energy charge increased maximally from 0.846 to 0.867 (P less than 0.001). The increase in the energy charge was accompanied by a concomitant decrease in the ADP levels (P less than 0.05). The respiratory control ration, state 3 respiration per unit of cytochrome a (+a3), and DNP-induced ATPase activity per unit of cytochrome a (+a3) increased significantly. The adenylate kinase and pyruvate kinase activities in the liver remained unchanged. On the other hand, the energy charge in the liver of alloxan-diabetic rats did not increase significantly after an oral glucose load. It was suggested that an increase in the energy charge of the liver is attributable to the more rapid flux of intermediary metabolism in the enhanced ADP-phosphorylating reactions by mitochondria, owing to an elevated level of insulin available to the hepatic cells.
...
PMID:Changes in adenylate energy charge of the liver after an oral glucose load. 17 25

Cellular membranes were prepared from the non-extending part of dark grown hypocotyls of Phaseolus aureus. The relative effectiveness of continuous and discontinuous sucrose gradient centrifugation for the separation of membranes was investigated. Characteristic densities of membranes were determined by the localization of enzyme activities on continuous sucrose gradients: NADH-cytochrome c-reductase for endoplasmic reticulum, beta-1-3-glucan synthetase for plasma-membrane and IDPase for dictyosomes. The difficulties involved in the application of ATPase and IDPase as specific membrane markers are discussed. Negative staining of isolated fractions indicated that intact dictyosomes could be prepared from this tissue without the use of chemical fixatives in the homogenization medium. Extraction of isolated membranes showed that carbohydrate-binding proteins (lectins) were present both in an easily removable and in a more strongly bound form. In vivo incorporation of D-[U-14C]glucose and subsequent isolation and solubilization of the different membranes showed that sugar-containing polymers could be released without hydrolytic techniques and were present in the equivalent extracts that exhibited lectin activity. The possibility of lectin-polysaccharide complexes in endoplasmic reticulum and dictyosomes and their involvement in the synthesis and transport of secretory substances by the membranes is discussed.
...
PMID:Characterization, enzymatic and lectin properties of isolated membranes from Phaseolus aureus. 18 22

Membrane vesicles isolated from untransformed Balb/c and Swiss mouse fibroblasts and their SV 40-transformed derivatives were shown to catalyze carrier-mediated, intravesicular uptake of alpha-aminoisobutyric acid and D-glucose. Concentrative uptake of alpha-aminoisobutyric acid required the presence of a Na+-gradient (external greater than internal) and could occur independently of endogenous (Na+ + K+)ATPase activity. A K+ diffusion gradient (internal greater than external) in the presence of valinomycin, or the addition of the Na+ salt of a highly permeant anion, conditions expected to create an interior-negative membrane potential stimulated Na+-gradient-dependent uptake, suggesting this process is electrogenic. D-Glucose uptake was nonconcentrative and did not require ion gradients or metabolic conversion. Na+ gradient-dependent transport of alpha-aminoisobutyric acid was reduced both in initial rate and extent of uptake in vesicles from confluent untransformed cells and increased in those from SV 40-transformed cells, compared with activities observed in vesicles from proliferating untransformed cells. No changes in D-glucose carrier activity were observed when assayed at low glucose concentrations.
...
PMID:Regulation of amino acid and glucose transport activity expressed in isolated membranes from untransformed and SV 40-transformed mouse fibroblasts. 18 48

Exposing micro-dissected pancreatic islets of non-inbred ob/ob mice to 2-5 mM-alloxan for 10 min decreased the ability of the islets to accumulate Rb+. Rb+ accumulation in pieces of exocrine pancreas was unaffected by alloxan. When islets were treated with alloxan in the presence of 2-20 mM-D-glucose, the Rb+-accumulating ability was protected in a dose-dependent manner. The protective action of D-glucose was reproduced with 3-O-methyl-D-glucose but not with L-glucose or D-mannoheptulose; mannoheptulose prevented D-glucose from exerting its protective action. The inhibition of Rb+ accumulation was due to a decreased inward pumping, since alloxan did not affect Rb+ efflux from pre-loaded islets. The inhibitory effect of alloxan had a latency of about 1 min, as revealed by experiments with dispersed islet cells in suspension. Alloxan-treated islets showed only a marginal decrease in ATP and no change in glucose 6-phosphate concentration. Although alloxan slightly decreased the hydrolysis of ATP in a subcellular fraction enriched in plasma membranes, this effect could not be attributed to a ouabain-sensitive adenosine triphosphatase. The plasma membranes exhibited a K+-activated hydrolysis of p-nitrophenyl phosphate; this enzyme activity too was insensitive to alloxan. Glucose may protect the univalent-cation pump by preventing permeation of alloxan via a path coupled to the hexose-transport system. Inhibition of the pump may be fundamental to the induction of alloxan-diabetes.
...
PMID:Alloxan cytotoxicity in vitro. Inhibition of rubidium ion pumping in pancreatic beta-cells. 19 15


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---