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)

In a unique Chinese hamster mutant, Gal-32, the mitochondrially encoded subunits of cytochrome c oxidase (CO I, II, III) and NADH dehydrogenase (ND 1-6) are greatly decreased while other mitochondrially synthesized proteins, such as ATPase subunits 6 and 8, are less affected. Pulse-chase experiments with [35S]methionine demonstrated that the reduced amounts of CO I and ND 5 subunits in Gal-32 are not the result of more rapid protein degradation. No differences in sizes of mtRNAs were detected between wild type and mutant using Northern blotting. The steady state levels of both heavy and light strand mtDNA transcripts were elevated in Gal-32: CO I mRNA was 1.5-fold higher in the mutant than in the wild type; ND 5 mRNA was 1.9-fold higher; ND 6 precursor RNAs were 1.4-fold higher and ATPase 6 and 8 mRNA (a single transcript) was 2.7-fold higher. Thus, the amounts of translation products are roughly correlated with the levels of mRNAs. The reduced levels of mitochondrially synthesized proteins in Gal-32 are the result of decreased translation of specific mRNAs, not increased degradation of mtRNAs.
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PMID:Elevated mitochondrial RNA in a Chinese hamster mutant deficient in the mitochondrially encoded subunits of NADH dehydrogenase and cytochrome c oxidase. 169 38

Purified glycolipids were tested for their ability to serve as acceptors of [14C]fucose from GDP-[14C]fucose as catalyzed by cell-free extracts and purified membrane fractions of human colorectal carcinoma cells, SW1116, cultured in serum-free medium. Purified lactotetraosyl ceramide (Gal beta 1----3GlcNAc beta 1----3Gal beta 1----4Glc-Cer or LcOse4Cer) and H-1 glycolipid (Fuc alpha 1----2Gal beta 1----3GlcNAc beta 1----3Gal beta 1----4Glc-Cer or IV2 Fuc alpha LcOse4Cer) stimulated incorporation of radioactivity into lipid-soluble glycolipid at a rate greater than ten times that of Lea glycolipid [Gal beta 1----3(Fuc alpha 1----4)GlcNAc beta 1----3Gal beta 1----4Glc-Cer or III4 Fuc alpha LcOse4Cer]. The enzymatic activities in crude and purified membrane fractions were optimized for substrate concentrations (glycolipid and GDP-fucose), detergent requirement (taurocholate), pH, time and protein. The radioactive product of H-1 fucosylation migrated as discrete and distinct bands on high-performance thin-layer chromatograms (HPTLC). Evidence for their identity with Leb fucolipid described previously [Fuc alpha 1----2Gal beta 1----3(Fuc alpha 1----4)GlcNAc beta 1----3Gal beta 1----4Glc-Cer or III4IV2 (Fuc alpha) LcOse4Cer] is presented. The radioactive product of LcOse4Cer fucosylation was mainly Lea fucolipid as determined by co-migration with authentic Lea fucolipid in three HPTLC systems as native and acetylated derivatives. Our results also indicated a low level of H-1 and Leb glycolipid synthesis from LcOse4Cer. On the basis of the optima, linearity for time, and enzyme-limiting conditions, we obtained a 12-19-fold purification of the LcOse4Cer and H-1 fucosyl transferase acceptor activities in three peaks of a sucrose gradient. The peak with the highest specific activity (peak 3) was highest in density and in Na+, K+, ATPase specific activity, although NADH-cytochrome-c reductase and UDP-GalNac transferase were also present in peak 3. The apparent Km values of LcOse4Cer acceptor activity and H-1 acceptor activity in peak 3 were significantly different (p less than 0.01) by statistical tests, 2.4 microM and 0.5 microM, respectively. These apparent Km values were much lower (10(3) X) and the pH optima were lower (4.8-5.3), than the corresponding properties reported for the alpha 1----3/alpha 1----4 fucosyl transferase purified from human milk. Our results suggest a role for the non-glycosidic moieties of the acceptors and/or the tissue-specific or primitive expression of these fucosyl transferase activities.
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PMID:Biosynthesis of Lewis fucolipid antigens in human colorectal carcinoma cells. Partial characterization of LcOse4Cer and H-1 fucolipid fucosyl transferase acceptor activities. 366 17

Cultured A6 epithelial cells from toad kidney form confluent monolayers with tight junctions separating the apical and basolateral membranes. These two membrane domains have distinct compositions and functions. Thus, sodium is actively transported across the epithelia from the apical to basolateral surface via amiloride-inhibitable sodium channels located in the apical membrane. Sodium transport is stimulated by vasopressin, cholera toxin, and 8-bromo-cAMP applied to the basolateral surface where the receptors, adenylate cyclase, and Na+/K+-ATPase are located. In a previous study (Spiegel, S., Blumenthal, R., Fishman, P.H., and Handler, J.S. (1985) Biochim. Biophys. Acta 821, 310-318), we demonstrated that exogenous gangliosides inserted into the apical membrane of A6 epithelia do not redistribute to the basolateral membrane. With the ability to vary selectively the ganglioside composition of the apical membrane, we examined the effects of gangliosides on sodium transport in A6 epithelia. When the apical surface of A6 epithelia were exposed to exogenous gangliosides, sodium transport in response to vasopressin, cholera toxin, and 8-bromo-cAMP was enhanced compared to epithelia not exposed to gangliosides. The effect was observed with bovine brain gangliosides, NeuAc alpha 2----3Gal beta 1----3GalNAc beta 1----4[NeuAc alpha 2----3]Gal beta 1----4Glc beta 1----Cer (GD1a) and Gal beta-1----3GalNAc beta 1----4[NeuAc alpha 2----3]Gal beta 1----4Glc beta 1----Cer (GM1), but not with the less complex ganglioside, Neu-Ac alpha 2----3Gal beta 1----4Glc beta 1----Cer (GM3). We examined A6 cells for endogenous gangliosides and found that, whereas GM3 was a major ganglioside, only trace amounts of GM1 and GD1a were present. Based on cell surface and metabolic labeling studies, these gangliosides were synthesized by the cells and were present on the apical as well as the basolateral surface. Bacterial sialidase, which hydrolyzes more complex gangliosides to GM1, was used to modify the endogenous gangliosides on the apical surface; after sialidase treatment, the epithelia were more responsive to vasopressin, cholera toxin, and 8-bromo-cAMP. Thus, gangliosides may be modulators of sodium channels present in the apical membrane of epithelial cells.
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PMID:Gangliosides modulate sodium transport in cultured toad kidney epithelia. 378 88

We report a method for the isolation of enriched fractions of intact Golgi apparatus from neurons of 10- to 12-day-old rat brains. Neurons were prepared according to a modified method of Farooq and Norton [J. Neurochem. 31, 887-894 (1978)]. Golgi-enriched fractions were obtained after centrifugation of postmitochondrial supernatants in a discontinuous sucrose gradient. Golgi fractions 1 and 2, recovered at the interfaces of 28-34% and 34-36% sucrose densities, respectively, were examined with morphometric and enzymatic methods. Morphometric analyses showed that 21-34% of fraction 1 and 11-29% of fraction 2 consisted of intact Golgi apparatus. Lysosomes, mitochondria, ribosomes, and rough endoplasmic reticulum contaminated fraction 1 (6-10%) and fraction 2 (14-26%). Golgi fraction 1 showed a 25- to 65-fold enrichment over neurons of UDP Gal:GlcNAc galactosyltransferase, CMP-sialic acid:lactosylceramide sialyltransferase, and PAPS:cerebroside sulfotransferase activities. Golgi fraction 2 showed a 8- to 23-fold enrichment over neurons of the activities of the above glycolipid- and glycoprotein-synthesizing enzymes. The activities of the possible marker enzymes rotenone-insensitive NADH-cytochrome c reductase, succinate-cytochrome c reductase, and arylsulfatase were low or minimally elevated in the Golgi fractions. A sevenfold enrichment of Na+, K+-ATPase activities was found in the Golgi fractions. This is consistent either with significant plasma membrane contamination or with the presence of this enzyme in the neuronal Golgi apparatus.
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PMID:Isolation and characterization of an enriched Golgi fraction from neurons of developing rat brains. 400 71

Chinese hamster subunits of mitochondrial respiratory Complex I (NADH-ubiquinone reductase), Complex IV (cytochrome c oxidase), and Complex V (oligomycin-sensitive ATPase) were identified by immunoprecipitation and/or Western immunoblotting with antibody to the corresponding beef heart complexes. In the Chinese hamster lung cell mutant Gal 32, cytochrome c oxidase activity and its mitochondrially synthesized subunits (I, II, and III) are substantially decreased, but a cytoplasmically synthesized subunit (IV) is present at wild type levels. Complex I activity and five of its subunits are greatly diminished in Gal 32; several of the affected Complex I subunits correspond in mobility to mitochondrial translation products. In contrast, ATPase activity and its mitochondrially and cytoplasmically synthesized subunits are not greatly modified in the mutant. Our data suggest that the ATPase complex contains two rather than one mitochondrially synthesized peptides. The simultaneous correction of this pleiotropic phenotype in a spontaneous revertant of Gal 32 selected for its ability to grow on galactose suggests that the Gal 32 phenotype is a consequence of a single mutation. Therefore, it is concluded that Complex I may contain a previously unrecognized mitochondrially synthesized subunit(s), and that the lowered activity of both Complex I and cytochrome c oxidase in the mutant is due to decreased levels of their mitochondrially encoded subunits.
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PMID:A novel mutation selectively decreases complex I and cytochrome c oxidase subunits in Chinese hamster mitochondria. 608 29

Saccharomyces cerevisiae and Schizosaccharomyces pombe cells were grown on D-glucose, D-galactose, D-fructose, D-mannose, maltose, trehalose and ethanol. All these substrates were separately added to cells thus grown and the onset and rate of acidification mediated by the plasma membrane H(+)-ATPase were determined. Irrespective of the growth substrate, the best triggers of acidification in both species were fructose, mannose and glucose (with average rates of 5.2, 5.0 and 4.8 nmol H+ per min per mg dry weight, respectively, for S. cerevisiae, and 4.5, 6.8 and 5.8 for S. pombe). These were followed in S. cerevisiae by galactose in Gal-, Man- and Tre-grown cells (about 0.40 nmol H+) and by maltose in Mal- and Tre-grown cells (about 0.15 nmol H+). Trehalose elicited some response in only ethanol-grown cells while ethanol itself was completely ineffective in activating the H(+)-ATPase. In S. pombe, however, maltose caused an acidification rate of 3.6 nmol H+ per min per mg dry wt., followed by EtOH (().38), Gal (0.13) and Tre (0.05). 6-Deoxy-D-glucose and 2-deoxy-D-glucose, not metabolized or improperly metabolized analogues of glucose, had no effect whatsoever. It appears that the sensor triggering the ATPase-activating pathway is a complex responding both to a glucose-type sugar (Glc, Man, Fru) and possibly identical with one of the glucose carriers, and to one of its metabolites, most probably fructose-6-phosphate.
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PMID:Both glucose-type monosaccharides and one of their metabolites are required for activation of yeast plasma membrane H(+)-ATPase. 780 58

We fused the yeast-derived sequences encoding the invertase, acid phosphatase and alpha-factor pre- and prepro-signal peptides (SP) to the Cyamopsis tetragonoloba (guar plant) alpha-galactosidase(alpha Gal)-encoding gene and expressed these gene fusions in yeast. Whereas the amount of fusion protein produced by each of the constructs did not vary significantly, the secretion efficiency of the fusion protein that carried the SP of the prepro-alpha-factor (MF alpha 1) was consistently found to be about 10% higher than that of the other fusions (99% vs. 90%). Furthermore, when the secretion of alpha Gal was directed by the invertase (SUC2) SP, the intracellular enzyme localized to the endoplasmic reticulum (ER), whereas use of the MF alpha 1 SP caused the intracellular enzyme to be outer-chain-glycosylated and processed by the KEX2 endoproteinase, implying that it had passed the ER. These results suggest that the pro-peptide of MF alpha 1 stimulates the efflux of the heterologous protein from the ER. Null mutants of PMR1 (encoding a Ca(2+)-dependent ATPase) are known to give higher secretion efficiencies for a number of different heterologous proteins. Therefore, we also studied the secretion of alpha Gal in a pmr 1 disruption mutant. Structural analysis of the enzyme secreted by the mutant cells showed that it was completely processed by KEX2 and outer-chain-glycosylated, although the length of the outer-chain carbohydrate moiety was reduced when compared with the enzyme secreted by wild-type cells. These results contradict the hypothesis advanced by Rudolph et al. [Cell 58 (1989) 133-145] that disruption of PMR1 causes the secretory pathway to bypass the Golgi apparatus.
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PMID:Effect of a pmr 1 disruption and different signal sequences on the intracellular processing and secretion of Cyamopsis tetragonoloba alpha-galactosidase by Saccharomyces cerevisiae. 838 51

The ability of cAMP response-element binding protein (CREB)-binding protein (CBP) to function as a co-activator for a number of transcription factors appears to be mediated by its ability to act as a histone acetyltransferase and through its interaction with a number of other proteins (general transcription factors, histone acetyltransferases, and other co-activators). Here we report that CBP also interacts with a novel ATPase termed Snf2-Related CBP Activator Protein (SRCAP). Consistent with this activity, SRCAP contains the conserved ATPase domain found within members of the Snf2 family. Transfection experiments demonstrate that SRCAP is able to activate transcription when expressed as a Gal-SRCAP chimera and that SRCAP also enhances the ability of CBP to activate transcription. The adenoviral protein E1A was found to disrupt interaction between SRCAP and CBP possibly representing a mechanism for E1A-mediated transcriptional repression.
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PMID:Identification of a novel SNF2/SWI2 protein family member, SRCAP, which interacts with CREB-binding protein. 1034 96

It was found that rabbit skeletal muscle sarcoplasmic reticulum (SR) contained two main gangliosides: NeuNAc alpha 2-->3 Gal beta 1-->4 Glc beta 1-->1'ceramide (GM3) and Gal beta 1-->3 GalNAc beta 1-->4(NeuNAc alpha 2-->3) Gal beta 1-->4 Glc beta 1-->1'ceramide (GM1), and that the most abundant ganglioside GM3 could positively modulate the SR Ca(2+)-ATPase activity. In this paper, the effect of GM1 on Ca(2+)-ATPase was further investigated and compared with that of GM3. The study demonstrates that GM1 has an opposite effect with respect to GM3 on the activity of SR Ca(2+)-ATPase. Using assays, including intrinsic and time-resolved fluorescence and fluorescence quenching, the conformational changes of SR Ca(2+)-ATPase induced by GM1 and GM3 were compared. Obtained results indicate that GM1 could make the Ca(2+)-ATPase molecules less compact in the hydrophilic domain but more compact in the hydrophobic domain, while GM3 makes the enzyme more compact in both the hydrophilic and hydrophobic domain. Homogeneous GM1 and GM3 with the same ceramide moiety had similar effects on SR Ca(2+)-ATPase activities compared to their natural counterparts, suggesting that the carbohydrate chain may be the key moiety of the ganglioside molecule to be responsible for the difference of the effect on enzyme activity.
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PMID:Antagonistic effect of ganglioside GM1 and GM3 on the activity and conformation of sarcoplasmic reticulum Ca(2+)-ATPase. 1048 82

SRCAP (SNF2-related CPB activator protein) belongs to the SNF2 family of proteins whose members participate in various aspects of transcriptional regulation, including chromatin remodeling. It was identified by its ability to bind to cAMP-responsive-binding protein (CREB)-binding protein (CBP), and it increases the transactivation function of CBP. The phosphoenolpyruvate carboxykinase (PEPCK) promoter was used as a model system to explore the role of SRCAP in the regulation of transcription mediated by factors that utilize CBP as a coactivator. We show that transcription of a PEPCK chloramphenicol acetyltransferase (CAT) reporter gene activated by protein kinase A (PKA) is enhanced 7-fold by SRCAP. In the absence of PKA this SRCAP-mediated enhancement does not occur, suggesting that SRCAP functions as a coactivator for PKA-activated factors such as CREB. Replacing the PEPCK promoter binding site for CREB with a binding site for Gal4 (DeltaCRE (cAMP-responsive element) Gal4 PEPCK-CAT reporter gene) blocks the ability of SRCAP to activate transcription despite the presence of PKA. Expression of a Gal-CREB chimera restores the ability of PKA to regulate transcription of the DeltaCRE Gal4 PEPCK gene and restored the ability of SRCAP to stimulate PKA-activated transcription. In addition, SRCAP in the presence of PKA enhances the ability of the Gal-CREB chimera to activate transcription of a Gal-CAT reporter gene that contains only binding sites for Gal4. SRCAP binds to CBP amino acids 280-460, a region that is important for CBP to function as a coactivator for CREB. Overexpression of a SRCAP peptide corresponding to this CBP binding domain acts as a dominant negative inhibitor of CREB-mediated transcription. Structure-function studies were done to explore the mechanism(s) by which SRCAP regulates transcription. These studies indicate that the N-terminal region of SRCAP, which contains five of the seven regions that comprise the ATPase domain, is not needed for activation of CREB-mediated transcription. SRCAP apparently has several domains that participate in the activation of transcription.
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PMID:Regulation of cAMP-responsive element-binding protein-mediated transcription by the SNF2/SWI-related protein, SRCAP. 1152 79


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