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)

The brush border of intestinal epithelial cells consists of an array of tightly packed microvilli. Within each microvillus is a bundle of 20-30 actin filaments. The basal ends of the filament bundles are embedded in and interconected by a filamentous meshwork, the terminal web, which lies directly beneath the microvilli. When calcium and ATP are added to isolated brush borders that have been treated with the detergent, Triton X-100, the microvillar filament bundles rapidly retract into and through the terminal web region. Biochemical studies of brush border contractile proteins suggest that the observed microvillar contraction is actomyosin mediated. We have shown previously that the major protein of the brush border's actin (Tilney, L. G., and M. S. Mooseker. 1971. Proc. Natl. Acad. Sci. U. S. A. 68:2611-2615). The brush border also contains a protein with the same molecular weight as the heavy chain subunit of myosin (200, 000 daltons). In addition, preparations of demembranated brush borders exhibit potassium-EDTA ATPase activity of 0.02 mumol phosphate/mg-min (22 degrees C); this assay is diagnostic for myosin-like ATPase isolated from vertebrate sources. Other proteins of the brush border include a 30,000 dalton protein with properties similar to those of tropomyosin, and a protein with the same molecular weight as the Z band protein, alpha-actinin (95,000 daltons). How these observations bear on the basis for microvillar movements in vivo is discussed within the framework of our recent model for the organization of actin and myosin in the brush border (Mooseker, M. S., and L. G. Tilney. 1975. J. Cell Biol. 67:725-743).
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PMID:Brush border motility. Microvillar contraction in triton-treated brush borders isolated from intestinal epithelium. 1 Dec 22

Luminal brush border and contraluminal basal-lateral segments of the plasma membrane from the same kidney cortex were prepared. The brush border membrane preparation was enriched in trehalase and gamma-glutamyltranspeptidase, whereas the basal-lateral membrane preparation was enriched in (Na+ + K+1)-ATPase. However, the specific activity of (Na+ + K+)-ATPase in brush border membranes also increased relative to that in the crude plasma membrane fraction, suggesting that (Na+ + K+)-ATPase may be an intrinsic constituent of the renal brush border membrane in addition to being prevalent in the basal-lateral membrane. Adenylate cyclase had the same distribution pattern as (Na+ + K+)-ATPase, i.e. higher specific activity in basal-lateral membranes and present in brush border membranes. Adenylate cyclase in both membrane preparations was stimulated by parathyroid hormone, calcitonin, epinephrine, prostaglandins and 5'-guanylylimidodiphosphate. When the agonists were used in combination enhancements were additive. In contrast to the distribution of adenylate cyclase, guanylate cyclase was found in the cytosol and in basal-lateral membranes with a maximal specific activity (NaN3 plus Triton X-100) 10-fold that in brush border membranes. ATP enhanced guanylate cyclase activity only in basal-lateral membranes. It is proposed that guanylate cyclase, in addition to (Na+ + K+)-ATPase, be used as an enzyme "marker" for the renal basal-lateral membrane.
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PMID:Preparation of renal cortex basal-lateral and bursh border membranes. Localization of adenylate cyclase and guanylate cyclase activities. 1 97

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

An attempt is made to reconcile experimental data dealing with, inter alia, cytoplasmic streaming in Characean algae, contraction in actomyosin systems. Na+- and -K+-simtulated ATPase activity and the ultrastructure of brush border microvilli. It is postulated that myosin molecules transfer energy from ATP to an actin-containing filament and that a high energy conformation is subsequently propagated along the filament. At regularly spaced intervals corresponding to the length of an actin-tropomyosin subunit, the propagation of high energy involves rejection of a pressure pulse in the direction of cytoplasmic streaming. Proteins in solution capable of storing the thermodynamic energy represented by the pressure pulse will either migrate in the opposite direction or conserve the quantized cytoplasmic flow generated by the actin-containing filaments. At sites where actin filaments are attached to the plasma membrane the high energy is propagated in another direction leading to expulsion of sodium ions and neutralization of the vectorial pressure pulse.
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PMID:The migrating thermodynamic quantum hypothesis for cytoplasmic streaming, sodium pumping and other cell biological phenomena, deduced from biofunctional considerations of the ultrastructure of brush border microvilli. 6 43

Sorbitol density gradient centrifugation applied to intestinal mucosa homogenates resulted in a complete separation of soluble calcium-binding protein from the bound fraction of calcium-binding protein, providing further documentation of the bound pool of calcium-binding protein. The peak of the bound calcium-binding protein was not associated with the major peaks of any of the markers used, but was associated with minor peaks of alkaline phosphatase, RNA, and glucose-6-phosphatase. Lack of association of bound calcium-binding protein with (Na+ + K+)-ATPase indicated that the bound calcium-binding protein is not on the basolateral membrane. Differential centrifugation fractionation indicated that the bound calcium-binding protein is not associated with nuclei or mitochondria. The bound calcium-binding protein also could not be detected in partially purified brush borders. Exclusion of the brush border and basolateral membranes as the location of the bound calcium-binding protein suggests an intracellular locale.
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PMID:Studies on the subcellular localization of the membrane-bound fraction of intestinal calcium-binding protein. 11 17

The localization of ATPase and thiamine pyrophosphatase in the digestive system of Ophiocephalus punctatus has been studied. In stomach ATPase is found in the free border of the mucosa, gastric glands, submucosal connective tissue nuclei and muscularis. Thiamine pyrophosphatase is localized only in the mucosa and gastric gland cells. In the intestine, pyloric caeca and rectum, ATPase is distributed along the brush border of the columnar epithelial cells, their nuclei and cytoplasm. Mild activity is also found in the nuclei of submucosa and muscularis. The activity is stronger in the intestine than in the other portions. Thiamine pyrophosphatase activity in these portions is restircted only to the goblet cells. In the liver ATPase activity is associated both with the cytoplasm and nucleus of the hepatic cells. Thiamine pyrophosphatase activity is maximum in the centro-lobular portion.
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PMID:Histochemical localization of adenosine triphosphatase and thiamine pyrophosphatase in the digestive system of a teleost fish, Ophiocephalus punctatus. 12 4

The distribution of (Na+ + K+) ATPase over the plasma membranes of the proximal convoluted tubule from canine renal cortex has been determined. Ultrathin frozen sections of this tissue were stained with rabbit antibodies to this enzyme and ferritin-conjugated goat antirabbit gamma-globulin. It is demonstrated that high concentrations of this enzyme uniformly line the intercellular spaces of this epithelium. The consequences of this observation are discussed in terms of the low resistant tight junctions of these tubules and the isotonic fluid transport which they support. Furthermore, antibodies to (Na+ + K+) ATPase recognize an antigen on the luminal surfaces of the tubules within the brush border. It is proposed that the enzyme is present in this region of the plasma membrane as well, although at much lower concentration. To further substantiate this conclusion, a brush border fraction has been purified from rabbit kidney and been shown to contain significant (Na+ + K+) ATPase. These results contradict earlier conclusions about the location of (Na+ + K+) ATPase in this tissue.
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PMID:Immunoferritin determination of the distribution of (Na+ + K+) ATPase over the plasma membranes of renal convoluted tubules. II. Proximal segment. 12 58

The localization of (Na+ + K+)-activated ATPase was investigated in isolated brush borders of rat small intestinal mucosa. The purity of the fractions has been checked by morphological and enzymatic criteria. The brush borders were found to contain a significant quantity of (Na+ + K+)-activated ATPase. Separation of isolated brush borders into their substructures suggests that (Na+ + K+)-activated ATPase is localized deeper within the brush border region than invertase. These findings are discussed in relation to active monosaccharide transport in the intestine.
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PMID:Subcellular localization of (Na+ + K+)-activated ATPase in the brush border membrane of the mucosal cell of the rat small intestine. 12 67

Lactoperoxidase-catalysed iodination was used to label intestinal epithelial cell sheets with 125I. The iodination was carried out under conditions that allowed little penetration of lactoperoxidase into the cells and membrane-bound 125I therefore provided an effective marker for following plasma-membrane fragments through subcellular-fractionation procedures. 2. After homogenization and isopycnic zonal centrifugation through sucrose gradients two peaks of membrane-bound 125I were detected. One coincided with brush border enzymes such as alkaline phosphatase, disaccharidases and L-leucine B-naphthylamidase, whereas the other was coincident with the major peak of (Na++K+)-stimulated ATPase (adenosine triphosphatase), which has been thought to be concentrated in the basolateral plasma membranes of these cells. Neither peak of 125I reflected the distribution of any marker for an intracellular organelle. 3. A larger proportion of the (Na++K+)-stimulated ATPase, and thus of the basolateral plasma-membrane material, was found in a crude 'mitochondrial' fraction. It was not readiily separated from mitochondria by conventional techniques of subcellular fractionation. 4. Treatment of the 'mitochondrial' fraction with digitonin increased the density of basolateral plasma membrane but had little effect on mitochondrial density. A purified preparation of digitonin-loaded basolateral plasma membranes was isolated at a density of 1.20-1.22 by isopycnic centrifugation. 5. The enzymic composition of this preparation of basolateral plasma membranes is compared with previous preparations isolated from intestinal mucosal 'scrape' materials and from isolated cells.
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PMID:Basolateral plasma membranes of intestinal epithelial cells. Identification by lactoperoxidase-catalysed iodination and isolation after density perturbation with digitonin. 12 58

Histochemical localization of adenosine triphosphatase and thiamine pyrophosphatase in the digestive system of the teleost fish, Heteropneustes fossilis has been studied. In the stomach, ATPase activity is observed in the mucosa, gastric glands and muscularis. The activity is stronger in the muscularis. Very weak TPPase activity is localized only in the mucosa and gastric glands. In the intestinal mucosa ATPase activity is stronger especially, along the brush border. Mild activity is also found in the connective tissue network and their nuclei, muscularis and serosa. In the posterior portion of the intestine and rectum, the localization pattern is similar to that of intestine but the activity is weaker. TPPase activity in the intestine and rectum is restricted only to the goblet shaped mucus secreting cells. In the liver, strong activity of ATPase and moderate activity of TPPase are found in the cytoplasm as well as the nuclei of the hepatic cells.
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PMID:Distribution of adenosine triphosphatase and thamine pyrophosphatase in the digestive system of Heteropneustes fossils. 13 69


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