Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rats received 0.1% lead acetate in their drinking water for 3 weeks or for 6 weeks, at which time renal brush border fractions were obtained for measurement of enzyme activity. Renal brush border preparations from Pb2+-exposed rats exhibited statistically significant decreases in the activity of gamma-glutamyl transpeptidase and alanine aminopeptidase after 3 or 6 weeks of treatment. There was an increase in the activity of alkaline phosphatase which was statistically significant after 3 weeks of Pb2+ exposure. The (Na+,K+) adenosine triphosphatase activity and urokinase activity, located in the basolateral membrane fractions, were unchanged by Pb2+ exposure, as were the protein and phospholipid contents of the brush border fractions. The results are compared to those following acute exposure to Pb2+ or Cd2+.
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PMID:Rat kidney brush border enzyme activity following subchronic oral lead exposure. 285 32

Marker enzyme activities of different subcellular fractions were analyzed in cortex homogenates from rat kidney after different periods (15, 30, 60, and 90 min) of warm ischemia. Lactate dehydrogenase, alanine aminopeptidase, N-acetyl-beta-D-glucosaminidase, and succinate-cytochrome c reductase were not altered by ischemia in these periods. ATPase (2,4-dinitrophenol-stimulated and azide-sensitive), 5'-nucleotidase, K-Mg-nitrophenylphosphatase decline within 30 min of ischemia, whereas the microsomal enzymes glucose-6-phosphatase and NADPH-cytochrome c reductase decreased not before 60 min of ischemia. The early decrease of ATPase and of plasma membrane enzymes can be regarded as a consequence of membrane alterations. This enzymatic approach may be helpful to evaluate pharmacological agents for preventing and reserving ischemic effects in kidneys in a rational manner.
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PMID:Changed enzyme activities in rat kidney during ischemia. 286 6

Particles found in bovine seminal vesicle secretion were enriched by centrifugation. They varied in size and morphology and contained Mg2+,Ca2+-activated ATPase, aminopeptidase A, alanyl aminopeptidase, gamma-glutamyl transpeptidase and dipeptidyl peptidase IV activities. Hyperactivation of sperm motility and the acrosome reaction were induced by these particles in epididymal spermatozoa suspended in a modified Ringer medium. The hyperactivation, analysed with a microscopic slide test, started within minutes of exposure to membrane particles and continued for 3-4 h, during which time spermatozoa underwent the acrosome reaction. Acrosome staining, phase-contrast microscopy and transmission electron microscopy revealed that the acrosome reaction started within 60 min at 37 degrees C and affected up to 80% of spermatozoa in 4 h. These membrane particles differed from those reported previously in other species in enzyme composition, function and organ of origin.
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PMID:Effect of secretory particles in bovine seminal vesicle secretion on sperm motility and acrosome reaction. 357 75

The localization of the membrane-associated thiol oxidase in rat kidney was investigated. Fractionation of the kidney cortex by differential centrifugation demonstrated that the enzyme is found in the plasma membrane. The crude plasma membrane was fractionated by density-gradient centrifugation on Percoll to obtain purified brush-border and basal-lateral membranes. Gamma-Glutamyltransferase, alkaline phosphatase and aminopeptidase M were assayed as brush-border marker enzymes, and (Na+ + K+)-stimulated ATPase was assayed as a basal-lateral-membrane marker enzyme. Thiol oxidase activity and distribution were determined and compared with those of the marker enzymes. Its specific activity was enriched 18-fold in the basal-lateral membrane fraction relative to its activity in the cortical homogenate, and its distribution paralleled that of (Na+ + K+)-stimulated ATPase. This association indicates that thiol oxidase is localized in the same fraction as (Na+ + K+)-stimulated ATPase, i.e. the basal-lateral region of the plasma membrane of the kidney tubular epithelium.
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PMID:Localization of the membrane-associated thiol oxidase of rat kidney to the basal-lateral plasma membrane. 612 81

Brush border membrane vesicles from rat small intestine were isolated by a Mg/EGTA precipitation method. Further fractionation either by free flow electrophoresis or by sucrose density gradient centrifugation leads to subfractions which differ with respect to enzyme enrichment factors, transport properties for D-glucose and protein pattern analyzed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. A relative enrichment of (Na+ + K+)-ATPase is found in one fraction, whereas in another fraction maltase, aminopeptidase M and alkaline phosphatase are relatively enriched. The fractions show different properties of D-glucose transport under tracer exchange conditions and a different inhibition of D-glucose transport by phlorizin and phloretin. These results indicate that the vesicles obtained from rat small intestine by this cation precipitation method are not homogeneous. The inhomogeneity cannot be due to a crosscontamination by membranes other than from the cell envelopment, as none of the fractions show a significant enrichment of succinate--cytochrome c oxidoreductase, KCN-resistant NADH oxidoreductase or glucosaminidase. The inhomogeneity might be due either to a crosscontamination by basal-lateral membranes or to membranes derived from epithelial cells not yet fully differentiated.
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PMID:Heterogeneity of brush-border-membrane vesicles from rat small intestine prepared by a precipitation method using Mg/EGTA. 641 69

A dog kidney epithelial cell line (MDCK), grown in monolayer, displayed in vitro an asymmetric localization of surface proteins. Aminopeptidase [alpha-aminoacylpeptide hydrolase (microsomal), EC 3.4.11.2] was found only in the apical face whereas Na+, K+-ATPase (ATP phosphohydrolase, EC 3.6.1.3) was found in the basolateral faces. These two faces are delineated by the junctional complex at which close cell-cell contact occurs. alpha-Actinin, a protein associated with plasma membranes, was concentrated near the region of cell-cell contact. When membrane proteins in the apical surface were crosslinked and subsequently removed from the surface by endocytosis, crosslinked antigens reappeared in the apical face at the region of cell-cell contact. Antigens that were not crosslinked were also (re)inserted in the same region. This process was not affected by cycloheximide, presumably because a large pool of apical membrane proteins (observed in small cytoplasmic vesicles) was used to replace the endocytosed antigens. It is psoposed that the region containing the junctional complex is involved in guiding apical membrane proteins to their final location.
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PMID:Apical membrane aminopeptidase appears at site of cell-cell contact in cultured kidney epithelial cells. 693 62

Following experimental rhabdomyolysis, animals become resistant to heme protein-induced acute renal failure (ARF). The goals of this study were to: (a) ascertain whether this resistance, previously documented only in vivo, is expressed directly at the proximal tubular cell level; (b) determine whether heme proteinuria (vs. other consequences of rhabdomyolysis) is its trigger; and (c) ascertain some of its subcellular determinants. Rats were injected with a borderline toxic dose of glycerol and 24 hours later proximal tubular segments (PTS) were isolated for study. Their vulnerability to diverse forms of injury (FeSO4-induced oxidant stress, hypoxia, Ca2+ ionophore, cytochalasin D, PLA2) was compared to that found in normal PTS. Post-glycerol PTS manifested significant resistance to each insult (decreased lactate dehydrogenase +/- N-acetyl-beta-D-glucosaminidase release). Protection against FeSO4 was virtually complete and it was associated with a 50% decrease in membrane lipid peroxidation. No decrease in hydroxyl radical generation was noted during the FeSO4 challenge (salicylate trap assessment), suggesting a primary increase in membrane resistance to attack. That PLA2 addition caused less deacylation, plasma membrane enzyme (alanine aminopeptidase) release, and LDH leakage from post-glycerol versus normal tubules supported this hypothesis. To test whether cytoresistance was specifically triggered by heme proteins (vs. being a non-specific filtered protein effect, or a result of endotoxin cascade activation), rats were injected with purified myoglobin, non-heme containing filterable proteins, or endotoxin. Only myoglobin induced cytoresistance. In vivo heme oxygenase inhibition (tin-protoporphyrin) did not block the emergence of cytoresistance and it was expressed despite Na,K-ATPase inhibition (ouabain) or cytoskeletal disruption (cytochalasin D). In vivo heat shock failed to protect. In conclusion, (1) rhabdomyolysis induces broad based proximal tubular cytoresistance; (2) heme proteinuria is its trigger; and (3) it is most easily explained by a primary increase in plasma membrane resistance to attack.
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PMID:Heme protein-induced tubular cytoresistance: expression at the plasma membrane level. 763 63

Cadmium has been recognized as an environmental contaminant. In oral cadmium intoxication, the immediate target organ is the gastrointestinal tract. The aim of the present work was to study the effect of cadmium on the intestinal absorption of L-threonine and on the aminopeptidase N activity in rabbit jejunum, after in vitro addition and/or oral administration of CdCl2 in drinking water. Results obtained show that cadmium decreases L-threonine absorption in the jejunal tissue. This effect seems to be due to an action mainly on active amino-acid transport at the mucosal border of the intestinal epithelium, because cadmium does not seem to modify the amino-acid diffusion across the intestinal epithelium. Cadmium also inhibits the (Na(+)-K+)-ATPase activity of the enterocyte, which might explain the inhibition of the Na(+)-dependent L-threonine transport. Nevertheless, a direct action of the cadmium ion on the carrier of active transport cannot be rejected. Cadmium modifies the aminopeptidase N activity when administered in drinking water for 4 d.
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PMID:Cadmium action on aminopeptidase N activity and L-threonine intestinal transport in rabbit. 791 22

A short treatment of dog renal brush-border membrane vesicles (BBMV) with sodium cholate, followed by dialysis of the detergent, reorients the polarity of H(+)-ATPase in the membrane and exposes its ATP binding sites to the extravesicular space, as previously shown with pig BBMV. In cholate-pretreated vesicles, the H(+)-ATPase remains fully active, but is inserted under the reversed polarity in sealed vesicles. A large spontaneous N-ethylmaleimide-sensitive ATPase activity is thus observed, as well as a steep intravesicular acidification upon external ATP addition, two findings absent in native vesicles. The ability of nitrate plus ATP to dissociate the hydrolytic subunits ot the proton pump in cholate-pretreated vesicles, but not in native vesicles, demonstrates that most of the ATP binding subunits are accessible to ATP following cholate treatment. The sensitivity of the cytoplasmic domain of the H(+)-ATP activity to trypsin also confirms the reorientation of the enzyme in cholate-pretreated vesicles. The H(+)-ATPase and alkaline phosphatase remain largely associated with the membranes after the treatment with cholate, but gamma-glutamyltranspeptidase, aminopeptidase N, and neutral endopeptidase are largely solubilized. Upon dialysis of cholate, all these enzymes are in part reinserted in the membrane according to their original polarity. The reorientation process is however specific for the H(+)-ATPase. Cholate treatment does not increase the formation of inside-out vesicles. Thus the treatment with cholate really reorients the polarity of the H(+)-ATPase in vesicles and allows for study of the proton pumping capacity of vacuolar H(+)-ATPase of proximal tubules.
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PMID:Effect of cholate on H(+)-ATPase and other proteins of dog renal brush-border membrane. 812 55

Clonal cell lines have been established from primary fetal rat intestinal epithelial cells by stable transfection with plasmids containing either the simian virus 40 (SV40) large T-antigen gene under the control of the heavy metal inducible metallothionein promoter (pMTWt) or the thermolabile SV40 T-antigen gene under the control of the SV40 early promoter (pZipSVtsa58). pMTWt-transfected cells produced sufficient T-antigen to allow them to proliferate both when the metallothionein promoter was induced and uninduced. No differences were observed in the pattern of intestinal epithelial markers expressed when the cells were cultured in the presence or absence of inducing agent (zinc). In contrast, fetal rat intestinal epithelial cells transfected with pZipSVtsa58 were immortalized conditionally; cells proliferated at 32 degrees C but ceased to proliferate between 48 and 72 h of culture at 39 degrees C. Four of these cell lines were characterized in detail; they showed microvilli and tight junctions as well as dome formation and expressed functional and biochemical markers of intestinal epithelial cells, including keratins 8, 19, and 21, aminopeptidase N, and dipeptidyl peptidase IV. One cell line, 2/4/A1, expressed in addition a low level of lactase and sucrase-isomaltase. The amount and/or activity of some of these markers changed during the switch from the proliferative to the nonproliferative state (switch from culture at 32 to 39 degrees C), resulting in a more differentiated phenotype and mimicking similar changes taking place during intestinal epithelial cell differentiation in vivo.
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PMID:Conditionally immortalized intestinal epithelial cells: novel approach for study of differentiated enterocytes. 839 82


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