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)

Centrifugation of homogenates of bovine retinas to isopycnic equilibrium in sucrose density gradients yielded three partially overlapping bands of particles which were, in the order of increasing density: (a) photoreceptor cell (rod) outer segments; (b) plasma membranes, lysosomes, and large fragments of endoplasmic reticulum; and (c) mitochondria. The only enzyme activity investigated which had a peak coinciding only with outer segment fractions was guanylate cyclase. Enzyme activities with peaks in both the outer segment and denser fractions included 5'-nucleotidase and cyclic GMP phosphodiesterase. Enzyme activities with peaks only in the denser fractions included sodium and potassium ion-activated ATPase ((Na+ + K+)-ATPase), adenylate cyclase, cyclic AMP phosphodiesterase, beta-glucosidase, beta-galactosidase, and succinate-dependent cytochrome c reductase. These results suggest that some of the activities once thought to be present in rod outer segments are actually present in particles from elsewhere in the retina which contaminate rod outer segment preparations.
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PMID:Distribution of enzyme activities in subcellular fractions of bovine retina. 0 65

The purpose of this work was to isolate thymocyte plasma membranes at high yield and purity to study specific surface molecules in their structural context. A procedure was developed in which 92-95% of the cells were disrupted by homogenization in a dense viscous medium, while nuclei remained intact. Differential centrifugation of the homogenate was avoided; instead, only a brief (2 h) centrifugation at equilibrium-density of membrane components was used. Five fractions were obtained, three by flotation. Membrane-bound enzymatic activities indicated a 60-80% yield of plasma membranes in the three floated membrane fractions, which comprised 1.6% of the homogenate protein. Enrichment factors for three ectoenzymes, alkaline phosphatase, gamma-glutamyltransferase, and ouabain-sensitive adenosine triphosphatase were respectively, 70-74, and 40-50 in the two lightest fractions. Nuclear membranes were then isolated from the remaining whole nuclei and were found to be enriched in esterase and NADH-cytochrome c reductase. Plasma membranes and light nuclear membranes appeared as pure unit-membrane vesicles in thin sections and freeze-etching electron microscopy. Some aggregation of intramembranous particles occurred in plasma membrane vesicles.
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PMID:Isolation of plasma and nuclear membranes of thymocytes. I. Enzymatic composition and ultrastructure. 2 89

A procedure for preparing highly purified brush border membranes from rabbit kidney cortex using differential and density gradient centrifugation is described. Brush border membranes prepared by this procedure were substantially free of basal-lateral membranes, mitochondria, endoplasmic reticulum and nuclear material as evidenced by an enrichment factor of less than 0.3 for (Na+ + K+)-ATPase, succinate dehydrogenase, NADPH-cytochrome c reductase and DNA. Alkaline phosphatase was enriched ten fold indicating that the membranes were enriched at least 30 fold with respect to other cellular organelles. The yield of brush border membranes was 20%. Transport of D-glucose by the membranes was identical to that previously reported except that the Arrhenius plot for temperature dependence of transport was curvilinear (EA = 11.3--37.6 kcal/mol) rather than biphasic. Transport of p-aminohippuric acid and uric acid were increased by the presence of NaCl, either gradient or preequilibrated. However, no overshoot was obtained in the presence of a NaCl gradient, and KCl and LiCl also produced equivalent stimulation of transport suggesting a nonspecific ionic strength effect. Uptakes of p-aminohippuric acid and uric acid were not saturable, and were increased markedly by reducing the pH from 7.5 to 5.6. Probenecid (1 mM) reduced p-aminohippuric acid and uric acid (50 muM) uptake by 49% and 21%, respectively. We conclude that the uptake of uric acid and p-aminohippuric acid by renal brush border membranes of the rabbit occurs primarily by a simple solubility-diffusion mechanism.
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PMID:Transport of p-aminohippuric acid, uric acid and glucose in highly purified rabbit renal brush border membranes. 3 45

The influence of the mode of preparation upon some of the characteristics of white adipose tissue plasma membranes and microsomes has been reported. Plasma membrane fractions prepared from mitochondrial pellet were shown to have higher specific activities of (Mg2+ + Na+ + K+)-ATPase than plasma membranes originating in crude microsomes. Isolation of fat cells by collagenase treatment was found to result in a decrease in specific activity of the plasma membrane enzymes; in plasma membranes prepared from isolated fat cells, the specific activity values obtained for (Mg2+ + Na+ +k+)-ATPase and 5'-nucleotidase were only 42% and 6.3% respectively of those obtained in plasma membranes prepared from whole adipose tissue. Purification of whole adipose tissue crude microsomes by hypotonic treatment caused extensive solubilization of the endoplasmic reticulum marker enzymes, NADH oxidase and NADPH cytochrome c reductase. The lability of endoplasmic reticulum marker enzymes, however, was found to be greatly diminished in the preparations from isolated fat cells. The possibility that NADH oxidase and NADPH cytochrome c reductase activities found in the plasma membranes are microsomal enzymes adsorbed by the plasma membranes is discussed. The peptide patterns as well as the NADH oxidase and NADPH cytochrome c reductase activity patterns of plasma membranes and purified microsomes were compared by means of sodium dodecyl sulfate or Triton X-100 polyacrylamide gel electrophoresis.
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PMID:Comparison of plasma membranes and endoplasmic reticulum fractions obtained from whole white adipose tissue and isolated adipocytes. 12 89

Very pure preparations of synaptic vesicles have been obtained from guinea pig cerebral cortex and from the electromotor synapses of Torpedo marmorata by density gradient centrifugation in a zonal rotor followed by chromatography on columns of glass beads of controlled pore size. Markers for soluble cytoplasm (lactate dehydrogenase), plasma and endoplasmic membranes membranes (Na-K-ATPase; acetylcholinesterase, NADPH-cytochrome c reductase], mitochondrial membranes [cytochrome oxidase] and lysosomes [acid phosphatase] were used to assess contamination and were undetectable. The only enzymes detected in the highly purified preparations from guinea pig cerebral cortex were Mg- and Ca-activated ATPases, but their content relative to acetylcholine fell on chromatography suggesting that they may be constituents of non-cholinergic vesicles. Lipids analyses of the highly purified vesicles confirmed earlier results and showed that glycolipids and lysolecithin are present in negligible amounts; this suggests that lysolecithin is not required for exocytosis of synaptic vesicles. A discussion of the probable limiting concentration of acetycholine in cerebral cortical vesicles derived solely from cholinergic terminals suggests that from 13 to 56% of the vesicles isolated are cholinergic, depending on the assumptions made.
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PMID:The preparation and characterization of synaptic vesicles of high purity. 13 27

1. The distributions of several enzymes and other marker components were examined after zonal centrifugations of whole homogenates from glucose-repressed Saccharomyces cerevisiae on sucrose and iso-osmotic Ficoll, and the composition and morphology of the fractions were investigated. 2. After high-speed zonal centrifugation most of the protein, acid and alkaline phosphatases, alkaline pyrophosphatase, adenosine monophosphatase, beta-fructofuranosidase, alpha-mannosidase, NADPH-cytochrome c oxidoreductase and an appreciable amount of phospholipid and sterol were non-sedimentable, i.e. were at densities below 1.09 (g/cm3). Most of the RNA was at p=1.06-1.08 in Ficoll and at p=1.09-1.11 in sucrose. 3. The bulk of the Mg2+-dependent adenosine triphosphatase (Mg-ATPase) was coincident with the main peak of phospholipid and sterol, at median density 1.10, which was also rich in smooth-membrane vesicles. In Ficoll, a minor peak of phospholipid and sterol at p-1.12-1.15 contained a smaller part of the oligomycin-insensitive Mg-ATPase and heavy membrane fragments. In sucrose, several minor peaks of Mg-ATPase were in the mitochondrial density range, and a peak of oligomycin-insensitive Mg-ATPase coincident with a minor peak of phospholipid and sterol at around p-1.25 contained heavy membrane fragments of high carbohydrate content, especially mannose. 4. Further purification of the oligomycin-insensitive Mg-ATPase containing membrane preparations was performed on Urografin gradients. 5. It is argued that the oligomycin-insensitive Mg-ATPase containing membranes are fragments of the plasma membrane, but have different densities because they contain different amounts of glycoprotein particles.
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PMID:Distribution of membranes, especially of plasma-membrane fragments, during zonal centrifugations of homogenates from glucose-repressed Saccharomyces Cerevisiae. 13 74

Four cytoplasmic mutants of Saccharomyces cerevisiae showing loss of mitochondrial rutamycin-sensitive ATPase activity but having significant cytochrome oxidase and NADH-cytochrome c reductase have been isolated. Genetic studies indicate the mutations to be closely linked to each other and have been assigned to a new locus, PHO1. The mutations show a low frequency of recombination with the OL12 locus, suggesting a linkage to this marker. They are not, however, linked to the OLI1 locus. Linkage of the ATPase mutations to the OLI2 locus is also indicated by restoration of wild-type diploids by sigma- clones that retain the segment of mitochondrial DNA carrying OLI2. Based on the recombinants issued from crosses of the mutants with a triple drug-resistant strain and an analysis of the resistance markers present in sigma- clones that are effective in restoring a wild-type phenotype, the PHO1 locus has been placed in the segment of DNA located between PAR1 and OLI2.
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PMID:Localization on mitochondrial DNA of mutations leading to a loss of rutamycin-sensitive adenosine triphosphatase. 13 92

A procedure was developed for the analytical isolation of brush border and basal lateral plasma membranes of intestinal epithelial cells. Brush border fragments were collected by low speed centrifugation, disrupted in hypertonic sorbitol, and subjected to density gradient centrifugation for separation of plasma membranes from nuclei and core material. Sucrase specific activity in the purified brush border plasma membranes was increased fortyfold with respect to the initial homogenate. Basal lateral membrane were harvested from the low speed supernatant and resolved from other subcellular components by equilibrium density gradient centrifugation. Recovery of Na, K-ATPase activity was 94%, and 61% of the recovered activity was present in a single symmetrical peak. The specific activity of Na, K-ATPase was increased twelvefold, and it was purified with respect to sucrase, succinic dehydrogenase, NADPH-cytochrome c reductase, nonspecific esterase, beta-glucuronidase, DNA, and RNA. The observed purification factors are comparable to results reported for other purification procedures, and the yield of Na, K-ATPase is greater by a factor of two than those reported for other procedures which produce no net increase in the Na, K-ATPase activity. Na, K-ATPase rich membranes are shown to originate from the basal lateral plasma membranes by the patterns of labeling that were produced when either isolated cells or everted gut sacs were incubated with the slowly permeating reagent 35S-p-(diazonium)-benzenesulfonic acid. In the former case subsequently purified Na, K-ATPase rich and sucrase rich membranes are labeled to the same extent, while in the latter there is a tenfold excess of label in the sucrase rich membranes. The plasma membrane fractions were in both cases more heavily labeled than intracellular protein. Alkaline phosphatase and calcium-stimulated ATPase were present at comparable levels on the two aspects of the epithelial cell plasma membrane, and 25% of the acid phosphatase activity was present on the basal lateral membrane, while it was absent from the brush border membrane. Less than 6% of the total Na, K-ATPase was present in brush border membranes.
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PMID:Analytical isolation of plasma membranes of intestinal epithelial cells: identification of Na, K-ATPase rich membranes and the distribution of enzyme activities. 13 16

Enzyme distribution profiles of clarified bovine mammary homogenates separated by equilibrium centrifugation on linear sucrose gradients suggested that several of the commonly utilized marker enzymes for rat liver are also valid markers for mammary cellular components. These marker enzymes include: Succinate dehydrogenase (mitochondria), nicotinamide adenine dinucleotide phosphate cytochrome c reductase and, to a lesser extent, retenone insensitive nicotinamide adenine dinucleotide cytochrome c reductase (endoplasmic reticulum), galactosyl transferase (Golgi apparatus), 5'-nucleotidase (plasma membranes), uric acid oxidase (microbodies), and acid phosphatase (lysosomes). Rotenone sensitive nicotinamide adenine dinucleotide cytochrome c reductase and sodium, potassium, magnesium-stimulated adenosine triphosphatase were widely distributed among subcellular fractions and are not valid marker enzymes. The boyant densities determined for the above fractions should aid in design of methods to obtain enriched sources of these components for analysis.
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PMID:Membranes of mammary gland. XI. Marker enzyme distribution profiles for membranous components from bovine mammary gland. 17 Dec 90

1. Functional properties of the ATPase complex are investigated in megamitochondria isolated from livers of weanling mice fed a diet containing 2% chloramphenicol, as an inhibitor of mitochondrial protein synthesis. 2. Whereas the specific activity of ATPase remains unchanged in chloramphenicol-induced megamitochondria, about 40% of the enyzme activity is resistant to inhibition by oligomycin, triethyltin or venturicidin. It is concluded that the ATPase complex lacks one or more components whose synthesis or accumulation is dependent on mitochondrial translation. The inhibitor-resistant ATPase portion appears tightly bound to the mitochondrial membrane. 3. Respiratory chain phosphorylation is tightly coupled in isolated megamitochondria. ATP synthesis and ATP-Pi exchange are diminished by 40%, as compared to control mitochondria, but both processes are sensitive to oligomycin, triethyltin or venturicidin. 4. The decrease in ATP synthesis and ATP-Pi exchange in megamitochondria correlates quite well with the emergence of inhibitor-resistant ATPase. 5. The following electron transport activities in the megmitochondria are reduced: NADH-cytochrome c reductase, by 60%, cytochrome oxidase, by 80%; the amount of antimycin required to gain complete inhibition of the bc1-segment is diminished by more than 50%. On the other hand succinate dehydrogenase activity is increased by 50%. 6. Chloramphenicol-induced megamitochondria appear to be a useful system for studying the role of mitochondrial translation in the assembly of mammalian mitochondria.
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PMID:ATPase complex and oxidative phosphorylation in chloramphenicol-induced megamitochondria from mouse liver. 17 30


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