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)

Alkaline phosphatase was released from protoplasts of the yeast Saccharomyces cerevisiae without cell lysis not only by phosphatidylinositol (PI)-specific phospholipase C but also by phosphatidylcholine (PC)-hydrolyzing phospholipase C. Activities of mitochondrial enzymes such as succinate dehydrogenase, antimycin-sensitive NADH-cytochrome c reductase, and oligomycin-sensitive ATPase were decreased by the action of PC-hydrolyzing phospholipase C. Hydrolysis of microsomal PC or PI did not cause any decrease in the activities of NADPH-cytochrome c reductase and antimycin-insensitive NADPH-cytochrome c reductase. In the requirement of phospholipids, the properties of yeast mitochondrial enzymes were very close to those of mammalian mitochondrial enzymes, whereas those of yeast microsomal enzymes were completely different from those of mammalian microsomal enzymes.
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PMID:Effects of phospholipases C on membrane-bound enzymes of yeast. 296 99

Sarcolemmal (SL) and microsomal (MC) membranes were prepared from adult canine cardiocytes. SL Na+, K+-ATPase (2.35 mumole/min per mg) was enriched 117-fold over the homogenate and MC rotenone-insensitive NADH cytochrome c reductase (RINCR) was enriched 41-fold. Preincubation of SL with 50 microM arachidonyl-CoA (20:4 CoA) stimulated Na+, K+-ATPase almost 2-fold; 250 microM 20:4 CoA inhibited the enzyme by 85%. However, RINCR was inhibited 80% by only 0.2 microM 20:4 CoA. Thus, each of these myocardial lipid-dependent enzymes showed a different sensitivity to perturbation by lipid amphiphiles. In further experiments, SL preincubated with 50 microM 20:4 CoA + 2.5 mM propranolol (which had no effect alone) exhibited a synergistic inhibition of the Na+, K+-ATPase: The enzymatic activity declined 8.5-fold when compared to sarcolemma treated with 50 microM 20:4 CoA alone. Thus, the presence of lipid amphiphiles may result in greater inhibition of the Na+, K+-ATPase when propranolol is present in the membrane.
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PMID:Perturbations of sarcolemmal and microsomal enzymes by amphiphilic lipids and drugs. 298 57

The calcium accumulating ability of mitochondria isolated both from bovine coronary artery and aorta was investigated. Coronary artery and aorta were pretreated with 0.1% collagenase. Cytochrome c oxidase activities of mitochondria isolated from coronary artery and aorta showed 25-fold and 19-fold increases, respectively, as compared with those of each homogenate, whereas NADPH-cytochrome c reductase, potassium-phosphatase and Na+-K+ ATPase activities increased less than 2-fold. This suggests that the isolation procedure is capable of obtaining a subcellular fraction highly enriched with mitochondria. Mitochondrial calcium uptake activity of the coronary artery was approximately 250 nmoles Ca2+/mg protein/10 min, and was markedly depressed with metabolic inhibitors such as NaN3, ruthenium red and 2,4-dinitrophenol. Calcium uptake activity of bovine aortic mitochondria showed similar activity and a similar trend in sensitivity to metabolic inhibitors. By contrast, the onset of the calcium binding reaction of the aortic mitochondria was slower and the azide-sensitivity of the mitochondria to magnesium ATPase activity was lower than those for coronary artery mitochondria. The present study has provided a method for isolation of mitochondria with a high capacity of calcium uptake activity, which may prove meaningful for future physiological and pharmacological evaluation of mitochondrial calcium accumulation in vascular smooth muscle.
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PMID:Calcium accumulating ability of mitochondria from bovine coronary artery. Comparison with aortic mitochondria. 298 75

The report deals with the effect of ischemia and reperfusion on purified sarcolemma obtained from canine myocardium of perfused supported heart preparations. Perfusion was carried out with a perfluorochemical (FC-43). Ischemia was produced by intermittent total clamping of inflow and outflow followed by release until the decrease in dP/dtmax had become stabile. Purity of sarcolemmal vesicles was ascertained with marker enzymes: succinate cytochrome c reductase (for mitochondria), K+-stimulated p-nitrophenylphosphate (K+-pNPPase), (Na+/K+)ATPase and adenylate cyclase (for SL). In addition Na+/Ca2+-exchange characteristics for SL were determined. Sidedness of vesicles was ascertained by means of adenylate cyclase activity using sarcolemmal preparations treated and untreated with alamethicin. Emphasis was placed on ATP-dependent Ca2+ uptake, phosphorylation of sarcolemmal vesicles and yield of SL proteins. Ischemia and reperfusion resulted in a significant reduction in adenylate cyclase activity. This decline was significant following ischemia and reperfusion. The yield of protein recovered from SL vesicles from ischemic-reperfused heart preparations was also significantly decreased. Both initial rate of ATP-dependent Ca2+ uptake and maximal Ca2+ uptake fell significantly following ischemia and reperfusion. The initial rate of phosphorylation also dropped significantly. These disturbances in SL Ca2+ transport following ischemia and reperfusion are probably a part of the general deficit in Ca2+ translocation.
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PMID:The effect of ischemia and reperfusion on sarcolemmal function in perfused canine hearts. 300 67

An accelerated method is developed for isolating a fraction of plasma membranes of pig myometrium using ultracentrifugation within the sucrose density gradient (15% and 30%). The membranes possessed the high activity of 5'-nucleotidase and Na+, K+-ATPase and the low activity of rhotenon-insensitive NADH-cytochrome c reductase. The vesicularized preparations of plasma membranes are able of ATP-dependent accumulation of Ca2+ (7.5 +/- 0.3 nmol. 45Ca2+ per 1 mg of protein for 15 min). Phosphate increases the calcium accumulation in the presence of ATP and Mg2+. Ionophore A 23187 promotes a complete and rapid release of the previously active-accumulated calcium. The release of 45Ca2+ accumulated by the membrane fraction may be reached by introduction of 1 mM EGTA or DS-Na into the incubation medium, that evidences for the cation accumulation inside closed structures. Using concanavalin-A-sepharose 4B it is shown that 60% of membrane vesicles are turned inside out. The low saponine concentrations (0.0005%) which inhibit Ca2+-accumulation by plasma membranes but not by the endoplasmic reticulum inhibit this process by 60-70% in preparations of the isolated membrane fraction. The method has certain advantages over the previously applied methods used for isolating of plasma membrane fragments from smooth muscles.
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PMID:[Isolation and characteristics of the plasma membrane fraction from the swine myometrium]. 301 62

Nuclear membranes of bovine corpora lutea contain nucleoside triphosphatase (NTPase), an enzyme involved in the nucleocytoplasmic transfer of mRNA. Upon addition to nuclear membranes, hCG stimulated this enzyme, but not Mg2+-ATPase or NADH cytochrome c reductase, in a dose-, time-, and temperature-dependent manner. Heat-denatured hCG, however, had no effect on NTPase activity. hCG antisera blocked hCG's ability to stimulate the NTPase activity. While human LH also stimulated luteal nuclear membrane NTPase activity, a variety of other hormones tested, including alpha- and beta-subunits of hCG and 1 and 10 mM cAMP, had no effect on the enzyme. hCG's effect on NTPase is tissue specific in that it had no effect on liver or kidney nuclear membrane NTPase activity. In conclusion, the present data demonstrate that hCG acts directly on the luteal cell nucleus, thus raising the possibility that internalized hCG might influence nuclear functions before it is eventually degraded in lysosomes of luteal cells.
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PMID:Direct stimulation of nucleoside triphosphatase activity in bovine luteal nuclear membranes by human chorionic gonadotropin. 303 92

We previously reported that nuclei isolated from ovaries of premenopausal women contain binding sites for hCG/human LH (hLH). This study was undertaken to determine the possible functional significance of these nuclear binding sites. Upon addition to isolated ovarian (mostly luteal cells) nuclear membranes, hCG and hLH stimulated nucleoside triphosphatase (NTPase), an enzyme involved in nucleocytoplasmic transfer of mRNA, but not Mg2+-ATPase or NADH cytochrome c reductase activities, in a concentration-dependent manner. Heat-denatured hCG, isolated alpha- and beta-subunits of hCG, human FSH, PRL, and porcine relaxin had no effect on the enzyme. Addition of hCG antiserum blocked hCG's ability to stimulate NTPase activity. cAMP, which is a second messenger in hCG- and hLH-stimulated steroidogenesis, had no effect on NTPase activity. These results, which demonstrate that hCG acts on human ovarian nuclei directly, raise the possibility that internalized hCG might influence nuclear function(s) before it is eventually degraded in the lysosomes of ovarian cells.
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PMID:Direct stimulation of nucleoside triphosphatase activity in human ovarian nuclear membranes by human chorionic gonadotropin. 303 4

We report a method for the isolation of enriched fractions of intact Golgi apparatus from neurons of 10- to 12-day-old rat brains. Neurons were prepared according to a modified method of Farooq and Norton [J. Neurochem. 31, 887-894 (1978)]. Golgi-enriched fractions were obtained after centrifugation of postmitochondrial supernatants in a discontinuous sucrose gradient. Golgi fractions 1 and 2, recovered at the interfaces of 28-34% and 34-36% sucrose densities, respectively, were examined with morphometric and enzymatic methods. Morphometric analyses showed that 21-34% of fraction 1 and 11-29% of fraction 2 consisted of intact Golgi apparatus. Lysosomes, mitochondria, ribosomes, and rough endoplasmic reticulum contaminated fraction 1 (6-10%) and fraction 2 (14-26%). Golgi fraction 1 showed a 25- to 65-fold enrichment over neurons of UDP Gal:GlcNAc galactosyltransferase, CMP-sialic acid:lactosylceramide sialyltransferase, and PAPS:cerebroside sulfotransferase activities. Golgi fraction 2 showed a 8- to 23-fold enrichment over neurons of the activities of the above glycolipid- and glycoprotein-synthesizing enzymes. The activities of the possible marker enzymes rotenone-insensitive NADH-cytochrome c reductase, succinate-cytochrome c reductase, and arylsulfatase were low or minimally elevated in the Golgi fractions. A sevenfold enrichment of Na+, K+-ATPase activities was found in the Golgi fractions. This is consistent either with significant plasma membrane contamination or with the presence of this enzyme in the neuronal Golgi apparatus.
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PMID:Isolation and characterization of an enriched Golgi fraction from neurons of developing rat brains. 400 71

The growing mycelia of Trichoderma reesei Rut-C30 are richly endowed with endoplasmic reticula and a variety of pleomorphic subcellular bodies. Mycelia of the culture growing in presence of avicel pH101 was fractionated in sucrose density gradients, and several morphologically and biochemically distinct fractions were isolated. Mycelia were homogenized in a Bead Beater, and the homogenate was freed of nucleus and wall fragments by low-speed centrifugation before fractionation. Organelle-free cytosol, which did not penetrate the gradient, contained (of the total) 72% of the vanadate-sensitive ATPase, 26% of carboxymethyl cellulase (CMCase), 2% of cytochrome c reductase, and 13% of the protein. Significant fractions separated on a gradient were light vesicles containing heavily stained material inside and ribosomes attached to the outside surface, intact vesicles resembling condensing vacuoles, large vesicles derived from the plasma membrane, and heavy vesicles containing crystalline material. The light-vesicle fraction contained a large portion of the cell-bound CMCase activity. The particle-bound ATPase and cytochrome c reductase activities were concentrated in heavy fractions. The fractionation in the presence of MgCl2 improved the preservation of subcellular bodies derived from the endoplasmic reticula. Although the CMCase activity of the light-vesicle fraction was 4 times higher than the activity in the heavy-vesicle fraction, the CMCase antibody-binding capacities of both fractions were about the same. This discrepancy between the catalytic activity and the antibody-binding capacity suggests that the heavy vesicles might have contained considerable amount of inactive CMCase compared with that present in the light vesicles.
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PMID:Subcellular fractionation of a hypercellulolytic mutant, Trichoderma reesei Rut-C30: localization of endoglucanase in microsomal fraction. 409 50

A method for isolating plasma membrane fragments from HeLa cells is described. The procedure starts with the preparation of cell membrane "ghosts," obtained by gentle rupture of hypotonically swollen cells, evacuation of most of the cell contents by repeated washing, and isolation of the ghosts on a discontinuous sucrose density gradient. The ghosts are then treated by minimal sonication (5 sec) at pH 8.6, which causes the ghost membranes to pinch off into small vesicles but leaves any remaining larger intracellular particulates intact and separable by differential centrifugation. The ghost membrane vesicles are then subjected to isopycnic centrifugation on a 20-50% w/w continuous sucrose gradient in tris-magnesium buffer, pH 8.6. A band of morphologically homogeneous smooth vesicles, derived principally from plasma membrane, is recovered at 30-33% (peak density = 1.137). The plasma membrane fraction contained a Na-K-activated ATPase activity of 1.5 micromole Pi/hr per mg, 3% RNA, and 13.8% of the NADH-cytochrome c reductase activity of a heavier fraction from the same gradient which contained mitochondria and rough endoplasmic vesicles. The plasma membranes of viable HeLa cells were marked with (125)I-labeled horse antibody and followed through the isolation procedure. The specific antibody binding of the plasma membrane vesicle fraction was increased 49-fold over that of the original whole cells.
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PMID:Isolation of plasma membrane fragments from HeLa cells. 423 70


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