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)

Membrane glycoproteins have been studied in the normal lactating mammary gland and R3230 AC mammary tumor of the rat. Plasma membrane-enriched fractions were obtained from these tissues by discontinuous sucrose gradient centrifugation of a microsomal preparation from the tissue homogenates. The lightest membrane fractions (F-1 and F-2) have the greatest enrichment of plasma membrane markers, with a 14- to 20-fold purification of 5'-nucleotidase and Na+-K+ -adenosine triphosphatase over the homogenate values in both tumor and normal tissues for F-1. Electron microscopy shows smooth membrane vesicles for these fractions. Polypeptide analysis by acrylamide gel electrophoresis shows essentially the same patterns for F-1 and F-2 and only relatively minor differences between membrane components of tumor and normal tissues. Glycoprotein analysis of the polyacrylamide gels by periodate-Schiff staining indicates more dramatic differences. Membrane Fraction F-1 from normal tissue contains two major glycoproteins, GP-II and GP-III, while Fractions F-2 and F-3 contain an additional glycoprotein, GP-I, with a higher apparent molecular weight. In the tumor, the component corresponding to GP-III is decreased or absent and a new component GP-IV is seen at a lower apparent molecular weight.
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PMID:Membrane glycoprotein differences between normal lactating mammary tissue and the R3230 AC mammary tumor. 12 79

Mitochondria from a rat mammary tumor (R3230AC) have been compared with mitochondria from pregnant and lactating rat mammary glands, with particular attention paid to inner membrane enzymes and Transport proteins. In the tumor the mitochondrial adenosine triphosphatase was not activated by 2,4-dinitrophenol, in contrast to the mammary mitochondria from lactating or pregnant rats. Translocation of adenosine diphosphate across the inner membrane was found to be more rapid in the tumor by virtue of lovered Km adenosine diphosphate and raised Vmax. Transport of phosphate and dicarboxylic acids occurred at similar rates in all three types of mitochondria. The inner membrane proteins were also examined directly by sodium dodecyl sulfate/polyacrylamide gel electrophoresis and some differences are noted. These results, although they indicate subtle differences between the inner mitochondrial membranes of tumor as compared with those of pregnant or lactating rat mammary glands, cannot form the basis of an explanation for enhanced glucose utilization and aerobic lactic acid production in this tumor.
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PMID:A comparative study of inner membrane enzymes and transport systems in mitochondria from R3230AC mammary tumor and normal rat mammary gland. 16 45

The effect of each of twelve mammalian lignan derivatives on the growth of human mammary tumor ZR-75-1 cells was examined. At a concentration less than 10 micrograms/ml, tumor cell growth was inhibited from 18-68%. The effect of 2,3-dibenzylbutane-1,4-diol(hattalin) was found to be strongest, inhibiting growth by 50% at a concentration (EC50) of 2.1 micrograms/ml. Hattalin inhibited membrane Na+, K(+)-ATPase of canine kidney cortex. It also inhibited the ATPase of the plasma membrane fraction from both cultured cells and a section of human breast cancer tissue at a concentration ranging from 0.5 to 2.0 mM. However, only a few percent of membrane ATPase from either ZR-75-1 cells or breast carcinoma tissue was inhibited by 2.0 mM of ouabain, suggesting that the target ATPase of hattalin was other than ouabain-sensitive ATPase. The relative incorporation of [3H]thymidine per 1 x 10(5) cells into the acid-precipitable fraction of ZR-75-1 cells was not affected by 1-50 micrograms/ml of hattalin, while a marked decrease resulted from 1-10 micrograms/ml of 5-fluorouracil (5-FU). These results suggest that the suppressive effect of hattalin on tumor cell growth may not occur through inhibition of DNA synthesis but rather partly by inhibition of the plasma membrane ATPase other than Na+ and K(+)-dependent ones.
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PMID:Antiproliferative activity of mammalian lignan derivatives against the human breast carcinoma cell line, ZR-75-1. 214 33

The synthetic "picket fence" porphyrin, tetra(o-acetamidophenyl)porphine (TAc), as a biological photosensitizer has been evaluated both in vitro and in vivo in mitochondria from the R3230AC mammary tumor. Studies in vitro, consisting of incubation of mitochondria with TAc at a concentration of 4.0 micrograms/ml followed by photolysis, result in the inhibition of cytochrome c oxidase, proton translocating ATPase, succinate dehydrogenase, and malate dehydrogenase. The diminution in activity of the first three enzymes is approximately 2-fold greater than that seen with Photofrin II under the same conditions. Although TAc exists as four isolable atropisomers, no differences among these different forms were observed in their photosensitized inhibition of mitochondrial enzymes. Administration to tumor-bearing rats of TAc i.p. at a dose of 25 mg/kg did result in accumulation of porphyrin within the mitochondria of the R3230AC tumor as determined by subsequent irradiation of isolated mitochondria. The potential utility of TAc and related porphyrins in cancer phototherapy is discussed.
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PMID:Picket-fence porphyrins as potential phototherapeutic agents. 283 16

We have described previously the isolation and characterization of five distinct subpopulations of tumor cells from a single spontaneous strain BALB/cfC3H mouse mammary tumor (Cancer Res., 38: 3174--3181, 3758--3763, 1978). Subpopulations 68H and 4.10 are polygonal and grow in epithelioid patterns in vitro, whereas subpopulations 66, 67, and 168 are fusiform and grow in lattice or fibroblast-like patterns. Line 4.10 produces tumors with distinctly glandular architecture, whereas the other four subpopulations produce poorly differentiated tumors with mixed epithelial-sarcomatous histological patterns. All five lines were evaluated for epithelial characteristics. Dome formation, characteristic of transporting epithelial cells, could be induced by dexamethasone or dimethyl sulfoxide only in line 4.10 cells. Antibodies to cell type-specific mammary epithelial antigens reacted with each of the subpopulations. All five subpopulations had ultrastructural features of epithelial cells, including desmosomes (all five lines), junctional complexes (68H, 4.10, early-passage 66 and 67 only; poorly defined in 168), and growth in cords demonstrating polarity (68H cells). Less definitive myoepithelial characteristics were also seen in four of the lines, including an incomplete reaction for Na+-K+-ATPase (4.10 cells), hemidesmosome-like junctions (168 and early-passage 66 cells), and pinocytotic vesicles at lower than normal frequency (66, 67, and 168 cells). Thus, none of the lines were distinctly myoepithelial. We conclude that the five subpopulations are epithelial cells that express a spectrum of epithelial characteristics.
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PMID:Epithelial characteristics of five subpopulations of a heterogeneous strain BALB/cfC3H mouse mammary tumor. 626 Mar 49

Biological and morphological differences in the mammary tumors of BALB/cfC3H and BALB/cfRIII mice are due to differences in the causative viruses. The C3H and RIII variants of the murine mammary tumor virus (MuMTV) might give origin to different mammary tumors by transforming different types of cell, i.e. epithelial or myoepithelial cells. The nature (epithelial or myoepithelial) of the neoplastic cells has been investigated by demonstrating their plasma membrane ATPase activities. We found that in normal murine mammary gland both epithelium and myoepithelium have Mg++ dependent ATPase activity, while the myoepithelium shows in addition an Na+K+ dependent ATPase activity. It is suggested that the results obtained exclude the participation of myoepithelium to the neoplastic growth and we ascribe the differences in mammary tumors of the two strains of mice to differences in the mechanisms of action of the virus variants.
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PMID:Cytogenesis of murine mammary tumors in BALB/cfC3H and BALB/cfRIII strains. 645 16

Na-K-ATPase plays a central role in a variety of physiological processes, including ion transport and regulation of cell volume. Our previous data showed that hyperoxia increased the expression of Na-K-ATPase alpha 1 and beta 1 mRNA in lung type II cells. We similarly show that hyperoxia (> or = 95% O2 for 24-48 h) increased steady-state mRNA levels in both Na-K-ATPase subunits in Madin-Darby canine kidney (MDCK) cells. The mechanism of gene regulation by hyperoxia was assessed. Stability of the Na-K-ATPase mRNA levels of both subunits was unchanged in hyperoxia-exposed MDCK cells. To determine whether gene transcription was augmented by hyperoxia, MDCK cells were transfected with a beta 1-subunit promoter-reporter construct. Transfection with the wild-type promoter (beta 1-817) revealed a 1.9 +/- 0.2-fold increase in promoter activity. Transfection with 5' deletion constructs identified a 61-base pair (bp) region between -102 and -41 that was necessary for this increase in promoter activity by hyperoxia. Incorporation of this 61-bp region into a minimal promoter (mouse mammary tumor virus) similarly increased promoter activity 2.3-fold in the presence of hyperoxia. This increase in promoter activity was not seen when MDCK cells were incubated with various concentrations of hydrogen peroxide. In summary, hyperoxia increased Na-K-ATPase beta 1-subunit mRNA steady-state level due to increased transcription in MDCK cells. A region necessary for this hyperoxic effect on beta 1 transcription is located between base pairs -102 and -41 on the promoter.
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PMID:Regulation of Na-K-ATPase gene expression by hyperoxia in MDCK cells. 948 24

Solid-state NMR spectroscopy is being used to determine the structures of membrane proteins involved in the regulation of apoptosis and ion transport. The Bcl-2 family includes pro- and anti-apoptotic proteins that play a major regulatory role in mitochondrion-dependent apoptosis or programmed cell death. The NMR data obtained for (15)N-labeled anti-apoptotic Bcl-xL in lipid bilayers are consistent with membrane association through insertion of the two central hydrophobic alpha-helices that are also required for channel formation and cytoprotective activity. The FXYD family proteins regulate ion flux across membranes, through interaction with the Na(+), K(+)-ATPase, in tissues that perform fluid and solute transport or that are electrically excitable. We have expressed and purified three FXYD family members, Mat8 (mammary tumor protein), CHIF (channel-inducing factor) and PLM (phospholemman), for structure determination by NMR in lipids. The solid-state NMR spectra of Bcl-2 and FXYD proteins, in uniaxially oriented lipid bilayers, give the first view of their membrane-associated architectures.
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PMID:Structural studies of apoptosis and ion transport regulatory proteins in membranes. 1474 97

The FXYD protein family consists of several small, single-span membrane proteins that exhibit a high degree of homology. The best-known members of the family include the gamma-subunit of the Na(+)-K(+)-ATPase and phospholemman (PLM), a phosphoprotein of cardiac sarcolemma. Other members of the family include corticosteroid hormone-induced factor (CHIF), mammary tumor protein of 8 kDa (Mat-8), and related to ion channels (RIC). The exact physiological roles of the FXYD proteins remain unknown. To better characterize the function of the members of the FXYD protein family, we expressed several members of the family in Madin-Darby canine kidney (MDCK) cells. All of the FXYD proteins, with the exception of PLM, were primarily found in the basolateral plasma membrane. Surprisingly, PLM, a previously characterized plasma membrane protein, was found to colocalize with the endoplasmic reticulum marker protein disulfide isomerase. Treatment of MDCK cells expressing PLM with an agonist of PKC caused some of the PLM to be redistributed to the plasma membrane. Site-directed mutagenesis of residues within the cytoplasmic domain of PLM indicated that a negative charge at Ser69 is necessary to shift the localization of PLM to the plasma membrane. In addition, other regions of PLM necessary for either its endoplasmic reticulum or plasma membrane localization have been elucidated. In contrast to PLM, the plasma membrane localization of CHIF and RIC was not altered by mutation of potential cytoplasmic phosphorylation sites. Overall, these results suggest that phosphorylation of specific residues of PLM may direct PLM from an intracellular compartment to the plasma membrane.
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PMID:Cytoplasmic targeting signals mediate delivery of phospholemman to the plasma membrane. 1637 42

The N-terminal domain of AR is known to engage a hormone-dependent interaction with its C-terminal ligand-binding domain, and this N/C interaction is known to modulate AR transcriptional activity. Using Xenopus oocytes as a model system to study transcriptional regulation in chromatin, we found that two previously reported N/C interaction-defective AR mutants, one with deletion of 23FQNLF27(ARDeltaF) and one with a Gly 21 to Glu mutation (ARG21E), were surprisingly inactive in activating transcription from various reporters assembled into chromatin. Further study using chromatin immunoprecipitation assay revealed that these mutants failed to bind both mouse mammary tumor virus-long terminal repeat and prostate-specific antigen enhancer assembled into chromatin. This defect is specific to chromatin because both mutants could bind to a consensus AR response element in vitro and activate transcription driven by mouse mammary tumor virus-long terminal repeat in transient transfection as effective as the wild-type AR. To further substantiate this novel finding, we established 293 cell lines that stably expressed either AR or ARDeltaF mutant in an inducible manner. Using these cell lines, we confirmed by using chromatin immunoprecipitation assay that AR but not ARDeltaF could bind to the endogenous prostate-specific antigen enhancer. Furthermore, we found that the ARDeltaF mutant interacts poorly with Brg1, the ATPase subunit of the chromatin-remodeling factor SWI/SNF. Taken together, our study reveals a novel role of AR N/C interaction in control of AR chromatin binding and suggests a working model that the proper N/C interaction is required for AR to recruit SWI/SNF complex, which in turn remodels chromatin to allow AR to bind to AR response elements in chromatin.
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PMID:A role of the amino-terminal (N) and carboxyl-terminal (C) interaction in binding of androgen receptor to chromatin. 1637 97


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