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)

Preparations of isolated brush border plasma membrane of Hymenolepis diminuta and H. microstoma possess the following enzymatic activities: alkaline phosphohydrolase (E.C. 3.1.3.1); Type I phosphodiesterase (E.E. 3.1.4.1); ribonuclease (E.C. 3.1.4.22); adenosine triphosphatase (E.C. 3.6.1.3); and 5'-nucleotidase (E.C. 3.1.3.5). The following enzymatic activities could not be demonstrated in either membrane preparation: Type II phosphodiesterase (E.C. 3.1.4.18); cyclic adenosine-3', 5'-monophosphate phosphodiesterase (E.C. 3.1.4.17); leucine aminopeptidase (E.C. 3.4.11.1); maltase (alpha-glucosidase; E.C. 3.2.1.20); and lactase (beta-galactosidase; E.C. 3.2.1.23). These data generally agree with those of previous studies in which similar membrane-bound enzymes were demonstrated in intact (living) worms.
 ...
PMID:A comparison of membrane-bound enzymes of the isolated brush border plasma membranes of the cestodes of Hymenolepis diminuta and H. microstoma. 628 Jan 22

Primary cultures of rabbit-kidney epithelial cells derived from purified proximal tubules were maintained without fibroblast overgrowth in a hormone-supplemented serum-free medium (Medium RK-1). A hormone-deletion study indicated that the primary cultures derived from purified rabbit proximal tubules required all of the three supplements in Medium RK-1 (insulin, transferrin, and hydrocortisone) for optimal growth but did not grow in response to EGF and T3. In contrast, the epithelial cells in primary cultures derived from an unpurified preparation of rabbit kidney tubules and glomeruli grew in response to EGF and T3, as well as insulin, transferrin, and hydrocortisone. These observations suggest that kidney epithelial cells derived from different segments of the nephron grow differently in response to hormones and growth factors. Differentiated functions of the primary cultures derived from proximal tubules were examined. Multicellular domes were observed, indicative of transepithelial solute transport by the monolayers. The proximal tubule cultures also accumulated alpha-methylglucoside (alpha-MG) against a concentration gradient. However, little or no alpha-MG accumulation was observed in the absence of Na+. Metabolic inhibitor studies also indicated that alpha-MG uptake by the primaries is an energy-dependent process, and depends upon the activity of the Na+/K+ ATPase. Phlorizin at 0.1 mM significantly inhibited 1 mM alpha-MG uptake whereas 0.1 mM phloretin did not have a significant inhibitory effect. Similar observations have been made concerning the Na+-dependent sugar-transport system located on the lumenal side of the proximal tubule, whereas the Na+-independent sugar transporter on the peritubular side is more sensitive to inhibition by phloretin than phlorizin. The cultures also exhibited PTH-sensitive cyclic AMP synthesis and brush-border enzymes typical of proximal cells. However, the activities of the enzymes leucine aminopeptidase, alkaline phosphatase, and gamma-glutamyl-transpeptidase were lower in the cultures than in purified proximal-tubule preparations from which they are derived.
 ...
PMID:Characterization of primary rabbit kidney cultures that express proximal tubule functions in a hormonally defined medium. 629 32

A conventional brush border membrane preparation, obtained by divalent cation precipitation of homogenates of rabbit renal cortex, was analyzed by countercurrent distribution in an aqueous dextran:polyethylene glycol two-phase system. The resulting fractions were assayed for the presence of the Na+/H+ antiporter and for a variety of biochemical marker enzymes. This analysis revealed four physically distinct membrane populations (A-D). Population A consisted of two subpopulations, A' and A", which were enriched an average of 49-fold in maltase; they were also highly enriched in alkaline phosphatase, leucine aminopeptidase, and Na+/H+ antiporter. On the basis of their marker contents, populations A' and A" appear to represent highly purified, functional brush border membrane vesicles. Population B was enriched twofold in NADPH-cytochrome c reductase and population C was enriched 12-fold in galactosyltransferase. Populations B and C accounted for 25% of the protein in the starting material and appear to reflect contamination of the brush border membrane preparation by subpopulations of endoplasmic reticulum and Golgi fragments. Population D was enriched in Na+/H+ antiporter, alkaline phosphatase, leucine aminopeptidase, Na-K-ATPase, and acid phosphatase but not maltase, NADPH-cytochrome c reductase, galactosyltransferase, or succinate dehydrogenase. Its identity is unclear, and it might consist of a multiplicity of populations from different origins.
 ...
PMID:Na+/H+ antiporter in membrane populations resolved from a renal brush border vesicle preparation. 633 Nov 75

In porcine interareolar placental epithelia, the following enzymes were demonstrated by histochemical methods after 30, 58, 80, 100, and 110 d of pregnancy, respectively: beta-N-acetylhexosaminidase, beta-galactosidase, beta-glucuronidase, alpha-mannosidase, acid phosphatase, alkaline phosphatase, nonspecific esterases, cytochrome oxidase, 5-nucleotidase, leucine aminopeptidase, adenosine triphosphatase, diaphorases (NADH, NADPH), glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, succinate dehydrogenase, isocitrate dehydrogenase (NAD, NADP), beta-hydroxybutyrate dehydrogenase, glycero-3-phosphate dehydrogenase, NAD-glycero-3-phosphate dehydrogenase, glutamate dehydrogenase (NAD, NADP), lactate dehydrogenase. The results show that most of the enzyme activities remained almost unchanged during the period of investigation. Only G-6-PDH and 6-PGDH activities increased within the uterine epithelium and nonspecific esterase activity within uterine as well as chorionic epithelia during the 2nd half of pregnancy. Within chorionic and uterine epithelia, hydrolases but not dehydrogenases demonstrated a higher activity at the bases of chorionic villi as compared to the apices and flanks of the latter. The action and influence of the demonstrated enzymes on metabolism, energy transfer, secretory, and resorptive activities of chorionic and uterine epithelia are discussed.
 ...
PMID:[Enzyme histochemical studies of the swine placenta. Histoptics of enzymes in interareolar placental epithelia]. 643 35

Expansion of the bile salt pool size in rats increases maximum excretory capacity for taurocholate. We examined whether increased bile salt transport is due to recruitment of centrolobular transport units or rather to adaptive changes in the hepatocyte. Daily sodium cholate (100 mg/100 g body wt) was administered orally to rats. This treatment was well tolerated for at least 4 d and produced an 8.2-fold expansion of the bile salt pool. This expanded pool consisted predominently (99%) of cholic and deoxycholic acids. Significantly increased bile salt transport was not observed until 16 h after bile acid loading, and maximum elevations of transport capacity to 2.3-fold of control required approximately 2 d. In contrast, maximum sulfobromophthalein excretion rates increased 2.2-fold as early as 4 h and actually fell to 1.5-fold increase at 4 d. We studied the possibility that this adaptive increase in bile salt secretory transport was due to changes in canalicular surface membrane area, lipid composition, or increased number of putative carriers. Canalicular membrane protein recovery and the specific activities of leucine aminopeptidase, Mg(++)-ATPase and 5'-nucleotidase activities were unaltered by bile salt pool expansion. The content of free and esterified cholesterol and total phospholipids was unchanged in liver surface membrane fractions compared with control values. In contrast, sodium cholate administration selectively increased specific [(14)C]cholic acid binding sites twofold in liver surface membrane fractions. Increased numbers of [(14)C]cholic acid receptors (a) was associated with the time-dependent increase in bile salt transport, and (b) was selective for the taurine conjugate of cholate and (c) was reduced by chenodeoxycholate. Changes in bile acid binding sites 16 h following taurocholate and chenodeoxycholate and the lack of change with glycocholate was associated with comparable changes in bile salt transport. In conclusion, selective bile salts increase bile salt transport in the liver through an adaptive increase in the density of putative bile acid carriers in liver surface membrane.
 ...
PMID:Regulation of bile salt transport in rat liver. Evidence that increased maximum bile salt secretory capacity is due to increased cholic acid receptors. 709 71

An LLC-PK1 cell culture model was used to evaluate for a direct protective effect of the pentoxifylline analogue HWA-448 in gentamicin nephrotoxicity at the cellular level. Cells exposed to 2 mM gentamicin for 6 days displayed a significant decrease in specific activities of leucine aminopeptidase, NaK ATPase, and N-acetyl glucosaminidase, and an increase in total cellular phospholipids (P < .05). Concomitant exposure to 0.125 mM HWA-448, a dose that did not alter cellular enzymes or total phospholipids under physiologic conditions, prevented the alterations in marker enzymes and total phospholipids induced by gentamicin (P < .05). Gentamicin binding and uptake studies revealed 0.125 mM HWA-448 had no effect on LLC-PK1 cell plasma membrane binding or cellular gentamicin uptake. We conclude that HWA-448 ameliorates gentamicin-induced alterations in LLC-PK1 cell enzymes and phospholipids by a mechanism independent of plasma membrane binding or cellular uptake.
 ...
PMID:HWA-448 reduces gentamicin toxicity in LLC-PK1 cells. 761 11

The endosomal pathway of the rat renal cortex was labeled by intravenous infusion of fluorescent dextran small enough to cross the glomerular ultrafiltration barrier and be taken up by luminal endocytosis. A fraction containing entrapped fluorescein was isolated from a cortical homogenate after differential centrifugation and Percoll density gradient centrifugation. This fraction has been dubbed heavy endosomes. To our surprise, small-particle flow cytometry techniques demonstrated that heavy endosomes are homogeneous for entrapped fluorescein dextran and the presence of H(+)-adenosinetriphosphatase activity. The abundance of heavy endosomes, combined with the findings that true endosomal populations are identifiable in other renal cortical fractions, led us to test whether heavy endosomes had the attributes of intermicrovillar clefts. First, we tested whether heavy endosomes vesiculate in vivo or in vitro. Vesicle-by-vesicle flow cytometry analysis of uptake of fluorescein dextran added to the homogenate demonstrated that virtually all the vesicles form in vitro (99 +/- 2%, n = 4). Second, the fraction contains markers associated with intermicrovillar clefts: clathrin light chains, actin, glycoprotein gp280, and gp330, the "Heymann antigen." The presence of the brush border enzyme markers gamma-glutamyl transpeptidase and leucine aminopeptidase in > 99% of the heavy endosomes confirms that the vesicles are of apical origin. The activity of the enzymes colocalized with entrapped markers but was tenfold less than in brush-border membrane vesicles. Heavy endosomes isolated from the rat renal cortex vesiculate in vitro and contain several intermicrovillar markers.
 ...
PMID:Heavy endosomes isolated from the rat renal cortex show attributes of intermicrovillar clefts. 794 52

Brush border (BBM) and basolateral membranes (BLM) of rat renal cortical cells separated by free flow electrophoresis revealed two distinct peaks of BBM-specific leucine aminopeptidase and Na+/K(+)-ATPase for BLM. PTH/PTH-related protein (PTHrP) receptors were identified in BBM and BLM. Specific binding of 125 pM [125I]chicken [Tyr36]-PTHrP-(1-36)amide [chPTHrP-(1-36)] to individual fractions of membranes separated by free flow electrophoresis overlapped with the leucine aminopeptidase and Na+/K(+)-ATPase profiles. Binding to pooled BBM was 53 +/- 5% (mean +/- SEM) of that to BLM (P < 0.01). In BBM and BLM, half-maximal inhibition of binding was obtained with 0.4-0.9 nM chPTHrP-(1-36) and 0.2-0.6 nM rat PTH-(1-34). Guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S; 100 microM) lowered chPTHrP-(1-36) binding to 50% of control levels, and half-maximal inhibition of binding was obtained with 480 and 8 nM GTP gamma S in BBM and BLM, respectively. Cross-linking of the PTH/PTHrP receptors with [125I]chPTHrP-(1-36) modified with N-hydroxysuccinimidyl-4-azidobenzoate revealed indistinguishable doublets of 83 and 73 kilodaltons in both BBM and BLM. Adenylyl cyclase was stimulated 6- and 10-fold by chPTHrP-(1-36) and GTP gamma S, respectively, in BLM and 1.3- and 1.9-fold in BBM. In conclusion, PTH receptors were recognized in both the basolateral and brush border membranes. Different receptor coupling to G-proteins and minimal cAMP stimulation in BBM provide evidence for PTH/PTHrP receptor isotypes and/or different postreceptor activation in BBM and BLM.
 ...
PMID:Apical and basolateral parathyroid hormone receptors in rat renal cortical membranes. 811 56

In this study, an attempt has been made to compare the most common species of tapeworms in carp: non-segmentary Khawia sinensis and segmentary Bothriocephalus acheilognathi on the basis of histoenzymatic examination of 8 enzymes, i.e. alkaline phosphatase, acid phosphatase, adenosine triphosphatase, nonspecific esterase alfa, succinic dehydrogenase, lactate dehydrogenase, leucine aminopeptidase and gamma-glutamylo transferase.
 ...
PMID:[Localization and activity of several enzymes in tissues of Bothriocephalus acheilognathi and Khawia sinensis tapeworms parasitizing carp]. 823 9

The transport of the amphiphilic organic anion, p-aminohippurate (PAH), across the luminal (brush-border) and contraluminal (basolateral) membrane of renal proximal tubule cells was studied with membrane vesicles isolated from bovine kidney cortex. On the basis of the enrichment of specific activities of marker enzymes, leucine aminopeptidase and Na+/K(+)-ATPase, brush-border and basolateral membrane vesicles can be obtained from bovine kidneys in reasonably pure form. The uptake of [3H]PAH into both brush-border and basolateral membrane vesicles was trans-stimulated by intravesicular PAH and by 2-oxoglutarate. In the absence of Na+, [3H]PAH/2-oxoglutarate exchange was cis-inhibited by unlabelled 2-oxoglutarate in the medium. In the presence of an inward Na+ gradient, 10 microM 2-oxoglutarate, but no other Krebs cycle derivative, cis-stimulated [3H]PAH uptake, indicating that a Na(+)-coupled dicarboxylate transporter and PAH/2-oxoglutarate exchanger cooperate in both membranes to enhance [3H]PAH uptake. [3H]PAH uptake showed a non-saturable and a saturable component with similar apparent Km values in brush-border and basolateral membranes. Although one negatively charged PAH molecule exchanges with one doubly negatively charged 2-oxoglutarate molecule the exchange was electroneutral. Probenecid inhibited [3H]PAH/2-oxoglutarate exchange in brush-border and basolateral membrane vesicles with indistinguishable kinetics. We conclude that similar or identical PAH transporters are located in brush-border and basolateral membranes of bovine kidney proximal tubule cells. This arrangement seems species-specific since a Na+ gradient plus 2-oxoglutarate caused concentrative [3H]PAH uptake in brush-border membrane vesicles from bovine, but not from rat kidney.
 ...
PMID:p-Aminohippurate/2-oxoglutarate exchange in bovine renal brush-border and basolateral membrane vesicles. 832 32


<< Previous 1 2 3 4 5 6 7 Next >>