Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.3.14 (ATP synthase)
 7,042 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Peroxisomes were isolated from bovine and rat liver by use of differential and density gradient centrifugations. 2. In the final density gradient (Nycodenz) a distinct peak of ATPase activity codistributed with the peroxisome marker catalase and was well separated from the bulk of the ATPase activity and from markers for other subcellular organelles. 3. The peroxisome-associated ATPase had a pH optimum of 7.5 and was inhibited by N-ethylmaleimide, by N,N'-dicyclohexylcarbodiimide and by 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, but was unaffected by up to 30 microM n-tributyltin chloride. 4. Prolonged incubation with oligomycin at high concentrations indicated that 50% of peroxisomal ATPase was resistant to this inhibitor. The oligomycin-sensitive ATPase activity required at least a four-fold higher ratio of inhibitor to protein for inhibition than mitochondrial ATPase did. It was concluded that oligomycin-sensitive and oligomycin-resistant ATPase may be associated with liver peroxisomes.
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PMID:Properties of ATPase activity associated with peroxisomes of rat and bovine liver. 183 59

The association of an ATPase with the yeast peroxisomal membrane was established by both biochemical and cytochemical procedures. Peroxisomes were purified from protoplast homogenates of the methanol-grown yeast Hansenula polymorpha by differential and sucrose gradient centrifugation. Biochemical analysis revealed that ATPase activity was associated with the peroxisomal peak fractions which were identified on the basis of alcohol oxidase and catalase activity. The properties of this ATPase closely resembled those of the mitochondrial ATPase of this yeast. The enzyme was Mg2+-dependent, had a pH optimum of approximately 8.5 and was sensitive to N,N'-dicyclohexylcarbodiimide (DCCD), oligomycin and azide, but not to vanadate. A major difference was the apparent Km for ATP which was 4-6 mM for the peroxisomal ATPase compared to 0.6-0.9 mM for the mitochondrial enzyme. Cytochemical experiments indicated that the peroxisomal ATPase was associated with the membranes surrounding these organelles. After incubations with CeCl3 and ATP specific reaction products were localized on the peroxisomal membrane, both when unfixed isolated peroxisomes or formaldehyde-fixed protoplasts were used. This staining was strictly ATP-dependent; in controls performed in the absence of substrate, in the presence of glycerol 2-phosphate instead of ATP, or in the presence of DCCD, staining was invariably absent. Similar staining patterns were observed in subcellular fractions and protoplasts of Candida utilis and Trichosporon cutaneum X4, grown in the presence of ethanol/ethylamine or ethylamine, respectively.
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PMID:A proton-translocating adenosine triphosphatase is associated with the peroxisomal membrane of yeasts. 288 51

Incubation of Trypanosoma cruzi mitochondrial ATPase (Fo-F1) with the xanthine oxidase system (XO), Fenton's reagent (Fe2+ + H2O2) and the ascorbate-Cu system, caused gradual loss of enzyme activity, which increased as a function of incubation time and rate of oxygen radical generation. The essential role of OH. radicals for ATPase inactivation was supported by a) the enzyme protection afforded by superoxide dismutase, catalase and mannitol, when using the XO system; b) the similar effect of mannitol and benzoate with Fenton's reagent; c) the similar effect of catalase, EDTA and histidine with the ascorbate-Cu system; d) the increased rate of ATPase inactivation by 1) the XO system supplemented with chelated iron, and 2) the ascorbate-Cu system supplemented with H2O2. Comparison of oxygen radical generators for their action on membrane-bound (Fo-F1) and soluble F1 revealed that ascorbate-Cu was the most effective one, possibly because of its capability of producing OH. radicals that react preferentially with the enzyme at their formation site.
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PMID:Inactivation of mitochondrial adenosine triphosphatase from Trypanosoma cruzi by oxygen radicals. 301 49

We studied a male newborn suffering from deficiency of ornithine transcarbamylase (OTC) that is due to a G-to-A substitution in codon 269 of the OTC gene. This study intends to define the cell biological mechanisms in this naturally occurring OTC mutation which may explain the mild clinical course in spite of the very low residual enzyme activity. Using immunogold labeling of thawed thin frozen sections of liver from this patient and a control liver, we analyzed the quantitative distribution of several mitochondrial proteins in the cytosol and the mitochondria of hepatocytes. In addition, the absolute volumes and surface densities of mitochondria and peroxisomes were determined. Our results show that the absolute volume of mitochondria in the patient's hepatocytes was increased to 141% (P < 0.001) without any change in the surface density indicating an increased number of mitochondria. In the patient's hepatocytes the peroxisomes were increased in size but not in number. The concentration of OTC was elevated in the cytosol (P < 0.001) and to a lesser extent in mitochondria (P < 0.01) of the patient's hepatocytes thus indicating a doubling of OTC relative to control liver cells. The quantity of OTC in mitochondria was 63% higher in diseased liver cells. By conventional thin section electron microscopy, mitochondria-like structures with poorly defined cristae and an electron-dense matrix were observed in the cytoplasm of the diseased hepatocytes. By immunoelectron microscopy, they contained the cytochrome c oxidase II subunit as well as DNA but lacked OTC, carbamylphosphate synthetase, F1-ATPase beta subunit and catalase. Thus it appears that these structures represent defective and probably degenerating mitochondria. Our data indicate that the reduced enzyme activity of the mutant OTC is partly compensated by an increased amount of enzyme molecules in the cytosol as well as mitochondria combined with an increase in the biogenesis of mitochondria.
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PMID:Ultrastructural, immunocytochemical and stereological investigation of hepatocytes in a patient with the mutation of the ornithine transcarbamylase gene. 764 31

Elements responsible for the transcriptional activity of the human ATP synthase beta-subunit (ATPsyn beta) gene promoter have been studied through transient expression in HepG2 hepatoma cells of a CAT gene connected with various 5'-deletion mutants of the 5'-flanking region. Promoter activity was mostly dependent upon a single CCAAT motif as well as a nearby Ets domain binding region. This last region contains two sites that bind Ets-related proteins present in liver nuclear extracts as well as recombinant purified Ets-1 protein. The ATPsyn beta promoter was trans-activated by Ets-1 and Ets-2 expression vectors, and this effect was lost when the Ets binding region was deleted. The Ets binding region of the ATPsyn beta promoter increased basal expression and conferred Ets-1- and Ets-2-dependent trans-activation to the herpes symplex thymidine kinase minimal promoter. A double-point mutation of the main Ets-binding site, which suppresses Ets binding, blocks Ets-dependent trans-activation. It is concluded that the gene for the mitochondrial ATPsyn beta is a target of transcriptional activation by members of the Ets family of transcription factors. It is suggested that Ets transcription factors may be involved in the enhanced expression of the ATPsyn beta gene in highly proliferating cells and in the coordinate transcription of nuclear genes for mitochondrial proteins.
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PMID:ETS transcription factors regulate the expression of the gene for the human mitochondrial ATP synthase beta-subunit. 779 71

The gene structure of the human ATP synthase alpha subunit (hATP1) was determined by cloning and sequencing. This gene is approximately 14 kbp in length and contains 12 exons interrupted by 11 introns. Mapping of the clones of hATP1 and Southern blot analysis of the genomic gene showed that there were a single copy of bona fide hATP1 gene and two pseudogenes. Primer extension and S1 mapping analysis showed the presence of multiple transcription initiation sites of the hATP1 gene. No TATA box or CAAT box was found near the transcription initiation sites. Comparison with the bovine gene showed that the 5'-flanking region of the hATP1 gene has an unconserved guanine-cytosine (GC) rich region, including several binding motifs of transcriptional factors, such as Sp1, AP-2, and GCF. By functional assay of gene expression, the basal promoter activity was located near the GC rich region. Comparison of the 5'-upstream region of the hATP1 gene with those of the genes for bovine ATP synthase alpha, human beta, and human gamma subunits indicated three common sequences, suggesting that putative cis-elements coordinate the expressions of the three subunit genes for the ATP synthase. The enhancer activities derived from the 5'-deletion mutants of a hATP1-CAT chimeric gene were different in cell lines from four different human tissues, suggesting the existence of cell type-specific gene regulation.
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PMID:Gene structure and cell type-specific expression of the human ATP synthase alpha subunit. 808 50

The mitochondrial F1-ATPase beta subunit (ATPase-beta) of Nicotiana plumbaginifolia is nucleus-encoded as a precursor containing an NH2-terminal extension. By sequencing the mature N. tabacum ATPase-beta, we determined the length of the presequence, viz. 54 residues. To define the essential regions of this presequence, we produced a series of 3' deletions in the sequence coding for the 90 NH2-terminal residues of ATPase-beta. The truncated sequences were fused with the chloramphenicol acetyl transferase (cat) and beta-glucuronidase (gus) genes and introduced into tobacco plants. From the observed distribution of CAT and GUS activity in the plant cells, we conclude that the first 23 amino-acid residues of ATPase-beta remain capable of specifically targeting reporter proteins into mitochondria. Immunodetection in transgenic plants and in vitro import experiments with various CAT fusion proteins show that the precursors are processed at the expected cleavage site but also at a cryptic site located in the linker region between the presequence and the first methionine of native CAT.
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PMID:Truncated presequences of mitochondrial F1-ATPase beta subunit from Nicotiana plumbaginifolia transport CAT and GUS proteins into mitochondria of transgenic tobacco. 815 82

Our previous work indicated that energy transduction, as measured by myocyte respiration, was inhibited by hydrogen peroxide, but the mitochondrial membrane potential was relatively unaffected. Therefore, we determined in the present study the critical steps in mitochondrial energy transduction by measuring the sensitivity to hydrogen peroxide of NADH-CoQ reductase, ATP synthase, and adenine nucleotide translocase in situ in myocytes. Adult rat heart cells were isolated using collagenase and incubated in the presence of 0.1-10 mM hydrogen peroxide for 30 min. Activities of NADH-CoQ reductase and oligomycin-sensitive ATP synthase were assayed enzymatically with sonicated myocytes, and adenine nucleotide translocase activities were determined by atractyloside-inhibitable [14C]ADP uptake of myocytes, permeabilized by saponin. The NADH-CoQ reductase and ATP synthase activities were inhibited to 77% and 67% of control, respectively, following an exposure to 10 mM hydrogen peroxide for 30 min. The adenine nucleotide translocase activities were inhibited in a concentration- and time-dependent manner and by 10 mM hydrogen peroxide to 44% of control. The dose-response relationship indicated that the translocase was the most susceptible to hydrogen peroxide among the three enzymes studied. Combined treatment of myocytes with 3-amino-1,2,4-triazole, 1,3-bis(2-chloroethyl)-1-nitrosourea and diethyl maleate (to inactivate catalase, to inhibit glutathione reductase activity, and to deplete glutathione, respectively) enhanced the sensitivity of translocase to hydrogen peroxide, supporting the view that the cellular defense mechanism is a significant factor in determining the toxicity of hydrogen peroxide. The results indicate that hydrogen peroxide can cause dysfunction in mitochondrial energy transduction, principally as the result of inhibition of adenine nucleotide translocase.
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PMID:Effects of hydrogen peroxide on mitochondrial enzyme function studied in situ in rat heart myocytes. 821 72

Analysis of the promoters of the bovine and human nuclear-encoded mitochondrial F0F1 ATP synthase alpha-subunit genes (ATPA) has identified several positive cis-acting regulatory regions that are important for basal promoter activity in human HeLa cells. We have previously determined that the binding of a protein factor, termed ATPF1, to an E-box sequence (CANNTG) located within one of these cis-acting regions is critical for transcriptional activation of the ATPA gene. In this article, we describe a second positive cis-acting regulatory element of the ATPA gene that is important for expression of the ATPA gene. We show that this cis-acting element also contains a binding site for a protein present in HeLa cells. On the basis of electrophoretic mobility shift patterns, oligonucleotide competition assays, and immunological cross-reactivity, we conclude that this protein factor is Yin-Yang 1 (YY1). Experiments carried out to examine the functional role of YY1 within the context of the ATPA promoter demonstrated that YY1 acts as a positive regulator of the ATPA gene. For example, when the YY1 binding site of the ATPA promoter was placed upstream of a reporter gene it was found to activate transcription in transient transfection assays. In addition, disruption of the YY1 binding site in the ATPA gene resulted in a loss of transcriptional activity. Furthermore, in cotransfection experiments overexpression of YY1 in trans was found to activate transcription of ATPA promoter-CAT constructs. Thus, at least two positive trans-acting regulatory factors, ATPF1 and YY1, are important for expression of the bovine and human F0F1 ATP synthase alpha-subunit genes.
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PMID:Nuclear factor YY1 activates the mammalian F0F1 ATP synthase alpha-subunit gene. 888 41

The storage of subunit c of mitochondrial ATP synthase, other hydrophobic peptides, and autofluorescent pigment in both late infantile (CLN2) and juvenile (CLN3) neuronal ceroid lipofuscinosis, but not in infantile (CLN1), has raised the question of abnormal mitochondrial function. We now report a partial deficiency in three types of fatty acid oxidation in intact skin fibroblasts from CLN2 and CLN3 patients, but not CLN1. We observed a statistically significant 33% reduction in palmitate (beta-oxidation; mainly mitochondrial) and lignocerate (beta-oxidation; mainly peroxisomal), and a 50% reduction in phytanic acid (alpha-oxidation; mainly peroxisomal) in the absence of exogenous carnitine. In contrast, when we measured fatty acid beta-oxidation (lignoceric acid and palmitic acid), in the same human skin fibroblasts, following lysis in the presence of carnitine, we found no difference in enzyme activity among normal, CLN1, CLN2, and CLN3. However, we did observe a 40% reduction in peroxisomal particulate (bound) catalase activity in CLN1 and CLN2 fibroblasts, which typically results from organellar lipid accumulation or a membrane abnormality. However, total catalase levels were normal, and Western blot analysis of this and three other major oxidant protective enzymes (Mn-dependent superoxide dismutase [MnSOD], CuZn-dependent superoxide dismutase [CuZnSOD], and glutathione peroxidase) were normal in CLN1, CLN2, and CLN3, as well as in liver from an animal (English Setter dog) model for CLN, which shows similar pathology and subunit c storage. Our data showing differences between CLN1 and forms CLN2 and CLN3 suggest some type of mitochondrial membrane abnormality as the source of the pathology in CLN2 and CLN3.
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PMID:Mitochondrial abnormalities in CLN2 and CLN3 forms of Batten disease. 897 98


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