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)

Young rats were force-fed for 3 days a purified diet devoid of threonine and a number of aspects relating to RNA metabolism in the livers were studied. The findings in the livers of rats force-fed the threonine-devoid diet in comparison with those force-fed the complete diet were as follows: a) poly(A)-mRNA was increased in nuclei and in polyribosomes; b) DNA-dependent RNA polymerases I and II activities were increased; c) in vitro release of 14C-orotic acid labeled RNA from nuclei revealed that transport was unchanged and nucleoside triphosphatase activity of nuclear envelopes was unchanged; d) polyribosomes (total, free and membrane-bound) shifted toward heavier aggregation and in vitro 14C-leucine incorporation into protein was increased; e) RNase activities (at pH 5.4, 7.6, 9.5) were essentially unaltered; and f) in vivo 14C-choline incorporation into microsomal membranes was increased. By administering selected inhibitors of RNA and protein synthesis, such as actinomycin D, alpha-amanitin or cycloheximide, prior to killing the rats force-fed the threonine-devoid or complete diet for 3 days, it was demonstrated that the stimulatory effect on hepatic polyribosomes and protein synthesis in the experimental group was dependent upon new synthesis of poly(A)mRNA and of protein.
 ...
PMID:Studies dealing with hepatic RNA metabolism in rats force-fed a threonine-devoid diet. 616 Feb 24

The amino acid sequence of the proteolipid subunit of the ATP synthase was analyzed in six mutant strains from Escherichia coli K12, selected for their increased resistance towards the inhibitor N,N'-dicyclohexylcarbodiimide. All six inhibitor-resistant mutants were found to be altered at the same position of the proteolipid, namely at the isoleucine at residue 28. Two substitutions could be identified. In type I this residue was substituted by a valine resulting in a moderate decrease in sensitivity to dicyclohexylcarbodiimide. Type II contained a threonine residue at this position. Here a strong resistance was observed. These two amino acid substitutions did not influence functional properties of the ATPase complex. ATPase as well as ATP-dependent proton-translocating activities of mutant membranes were indistinguishable from the wild type. At elevated concentrations, dicyclohexylcarbodiimide still bound specifically to the aspartic acid at residue 61 of the mutant proteolipid as in the wild type, and thereby inhibited the activity of the ATPase complex. It is suggested that the residue 28 substituted in the resistant mutants interacts with dicyclohexylcarbodiimide during the reactions leading to the covalent attachment of the inhibitor to the aspartic acid at residue 61. This could indicate that these two residues are in close vicinity and would thus provide a first hint on the functional conformation of the proteolipid. Its polypeptide chain would have to fold back to bring together these two residues separated by a segment of 32 residues.
 ...
PMID:Identification of amino-acid substitutions in the proteolipid subunit of the ATP synthase from dicyclohexylcarbodiimide-resistant mutants of Escherichia coli. 625 67

Cultured chicken heart mesenchymal cells are proliferatively quiescent at low densities in medium containing plasma at 10%. Mitogenic hormones like epidermal growth factor and insulin-like growth factors cause these cells to proliferate very actively, as does infection with avian sarcoma viruses, erythroblastosis virus, or myelocytomatosis virus. We have found that the combination of phorbol 12-myristate 13-acetate (PMA), ionomycin or ouabain, and raised extracellular magnesium, likewise, causes these cells to proliferate very actively. Although these agents have no significant effect when acting singly, the combination of PMA at 100 ng/ml and 0.5 microM ionomycin induces a 6-fold increase in cell number at 4 days, and the combination of PMA, ionomycin, and 5.6 mM magnesium induces 12-fold multiplication. Likewise, PMA plus 1 microM ouabain induces 3-fold multiplication, whereas the combination of PMA, ouabain, and magnesium induces 6-fold multiplication. The tumor promoter PMA, like diacylglycerol released by breakdown of plasma membrane phosphatidylinositol diphosphate, is known to activate the serine- and threonine-specific intracellular enzyme kinase C. The divalent cation ionophore ionomycin is known to carry calcium into cells down an electrochemical gradient, and the Na+,K+-ATPase inhibitor ouabain appears to elevate intracellular calcium by means of a sodium-mediated exchange mechanism. Magnesium, like calcium, is known to enter cells passively down an electrochemical gradient and to be involved in the regulation of many key intracellular reactions. Our findings with PMA, ionotropes, and magnesium support a hypothesis that diacylglycerol-mediated activation of kinase C plus cellular divalent cation influx and/or mobilization, caused by the action of mitogenic hormones or the protein products of onc genes, are key events in the initiation of cell replication.
 ...
PMID:Phorbol 12-myristate 13-acetate, ionomycin or ouabain, and raised extracellular magnesium induce proliferation of chicken heart mesenchymal cells. 633 83

Procyclic culture forms of Trypanosoma brucei stock 427 have been screened for the presence of enzymes involved in glycolysis, mitochondrial energy metabolism and threonine degradation. The enzyme activities in the procyclics were compared with those of the blood stream forms. The specific activities of glycolytic enzymes represented 30-70% of the respective levels in the blood stream form, except for hexokinase which was 25-fold reduced. Cell fractionation showed that the enzymes involved in the early sequence of the glycolytic pathway, i.e. from hexokinase to phosphoglycerate kinase, and the enzymes NAD+-linked glycerol-3-phosphate dehydrogenase and glycerol kinase were all present in glycosomes equilibrating at a density of 1.23 g/cm3 in sucrose gradients. Malate dehydrogenase was 8-fold more active in procyclics than in bloodstream forms. This increase in activity was the result of the appearance of malate dehydrogenase in the glycosomes of the procyclics, in addition to mitochondrial and cell-sap activities which were present in both stages of the life cycle. Glycosomes contained part of the adenylate kinase activity, which was also associated with the mitochondrion. Succinate dehydrogenase and sn-glycerol-3-phosphate dehydrogenase, together with oligomycin-sensitive ATPase, were located in the mitochondrion which had a density in sucrose ranging from 1.16 to 1.18 g/cm3. This organelle also contained L-threonine 3-dehydrogenase and carnitine acetyltransferase, two enzymes involved in threonine catabolism. The latter two enzymes had activities which were, respectively, 15-and 13-fold higher in the procyclics than in the bloodstream form. Mitochondrial sn-glycerol-3-phosphate dehydrogenase was decreased 4-fold.
 ...
PMID:Localization of malate dehydrogenase, adenylate kinase and glycolytic enzymes in glycosomes and the threonine pathway in the mitochondrion of cultured procyclic trypomastigotes of Trypanosoma brucei. 680 9

Five peptide analogs of the actomyosin ATPase inhibitory region of troponin I (Tn-I) have been synthesized by the solid-phase method. One analog was constructed with a sequence identical to that found in species of Tn-I isolated from chicken fast, rabbit fast and rabbit slow skeletal muscle. A second peptide was made identical to the sequence of the homologous inhibitory region of Tn-I from rabbit cardiac muscle. The remaining three analogs were hybrids of the two sequences. We have verified that rabbit skeletal fast Tn-I was a better inhibitor than rabbit cardiac Tn-I in a rabbit skeletal actomyosin assay system and extended these studies to show that the same results were found in an assay system which used rabbit cardiac actomyosin. Our skeletal fast muscle peptide analog was also a better inhibitor in both assay systems than the cardiac Tn-I peptide analog. The hybrid peptides indicated that the changing of proline 110 to a threonine residue had no effect and suggested that position 110 was not essential to inhibition. The other amino acid change, the replacement of arginine 113 by a leucine residue, was shown to be the crucial difference and resulted in lower activity. Thus, th differences in relative inhibitory activity of rabbit skeletal fast and cardiac Tn-I can be at least partially and possibly solely explained by the single amino acid substitution at position 113. Short active sequences of proteins, like the Tn-I inhibitory region are potentially of enormous value as probes of structure-function relationships.
 ...
PMID:Comparative studies on the inhibitory region of selected species of troponin-I. The use of synthetic peptide analogs to probe structure-function relationships. 729 62

The substitution of arginine at position 210 in the alpha subunit of Escherichia coli F0F1-ATPase by either lysine or alanine causes dominance in complementation tests with a chromosomal c subunit mutation. Reversal of dominance was achieved for the alpha R210K mutation but not for the alpha R210A mutation by the presence of an aspartic acid residue at position 50 or at position 252 in the alpha subunit. It was concluded that position 210 in putative helix 4 of a previously proposed model of the alpha subunit is close to position 252 in putative helix 5 and to position 50 in putative helix 1. The juxtaposition of residues 252 and 210 was also indicated by the observation that the double mutant alpha R210Q/Q252R was partially functional. A revertant of the partially functional double mutant, isolated on succinate medium, was found to contain a third mutation resulting in Pro-204 in the alpha subunit being replaced by threonine. That the revertant phenotype was due to the alpha P204T change was confirmed by site-directed mutagenesis. ATP synthesis in the revertant strain was at near normal levels as judged by growth yield experiments, but the revertant strain was unable to pump protons in response to ATP hydrolysis.
 ...
PMID:The essential arginine residue at position 210 in the alpha subunit of the Escherichia coli ATP synthase can be transferred to position 252 with partial retention of activity. 749 77

PotA protein, one of the components of the spermidine-preferential uptake system in Escherichia coli, was purified to homogeneity, and some of its properties were examined. PotA protein showed Mg(2+)-and SH-dependent ATPase activity. The specific activity was approximately 400 nmol/min/mg of protein and the Km value for ATP was 385 microM. The nature of the ATP binding site was explored by identification of the amino acid residue photoaffinity-labeled with 8-azido-ATP. It was found that 8-azido-ATP was attached to cysteine 26. In the spermidine transport-deficient mutant E. coli NH1596, valine 135 of PotA protein, which is located between two consensus amino acid sequences for nucleotide binding (50-57 and 168-173), was replaced by methionine (Kashiwagi, K., Miyamoto, S., Nukui, E., Kobayashi, H., and Igarashi, K. (1993) J. Biol. Chem. 268, 19358-19363). This mutated PotA protein could be labeled with 8-azido-ATP, but showed very low ATPase activity. To identify which cysteine is involved in the function of potA protein, cysteines 26, 54, and 276 were replaced by alanine, threonine, and alanine, respectively. Among the three mutated PotA proteins, the mutated PotA protein C54T only lost both ATPase and spermidine uptake activities. The results taken together indicate that the adenine portion of ATP interacts with a domain close to the NH2-terminal end of PotA protein, and active centers of ATP hydrolysis are located both within and between the two consensus amino acid sequences for nucleotide binding. Association of PotA protein with membranes was strengthened by the existence of channel forming PotB and PotC proteins. ATPase of PotA protein was inhibited by spermidine, suggesting that uptake inhibition by spermidine may function during this process.
 ...
PMID:Spermidine-preferential uptake system in Escherichia coli. ATP hydrolysis by PotA protein and its association with membrane. 759 3

ClpA is the ATPase component of the ATP-dependent protease Ti (Clp) in Escherichia coli and contains two ATP-binding sites. A ClpA variant (referred to as ClpAT) carrying threonine in place of the 169th methionine has recently been shown to be highly soluble but indistinguishable from the wild-type, 84-kDa ClpA in its ability to hydrolyze ATP and to support the casein-degrading activity of ClpP. Therefore, site-directed mutagenesis was performed to generate mutations in either of the two ATP-binding sites of ClpAT (i.e. to replace the Lys220 or Lys501 with Thr). ClpAT/K220T hydrolyzed ATP and supported the ClpP-mediated proteolysis 10-50% as well as ClpAT depending on ATP concentration, while ClpAT/K501T was unable to cleave ATP or to support the proteolysis. Without ATP, ClpAT and both of its mutant forms behaved as trimeric molecules as analyzed by gel filtration on a Sephacryl S-300 column. With 0.5 mM ATP, ClpAT and ClpAT/K501T became hexamers, but ClpAT/K220T remained trimeric. With 2 mM ATP, however, ClpAT/K220T also behaved as a hexamer. These results suggest that the first ATP-binding site of ClpA is responsible for hexamer formation, while the second is essential for ATP hydrolysis. When trimeric ClpAT/K220T was incubated with the same amount of hexameric ClpAT/K501T (i.e. at 0.5 mM ATP) and then subjected to gel filtration as above, a majority of ClpAT/K220T ran together with ClpAT/K501T as hexameric molecules. Furthermore, ClpAT/K501T in the mixture strongly inhibited the ability of ClpAT/K220T to cleave ATP and to support the ClpP-mediated proteolysis. Similar results were obtained in the presence of 2 mM ATP and also with the mixture with ClpAT. On the other hand, the ATPase activity of the mixture of ClpAT and ClpAT/K220T was significantly higher than the sum of that of each protein, particularly in the presence of 2 mM ATP, although its ability to support the proteolysis by ClpP remained unchanged. These results suggest that a rapid exchange of the subunits, possibly as a trimeric unit, occurs between the ClpAT proteins in the presence of ATP and leads to the formation of mixed hexameric molecules.
 ...
PMID:Distinctive roles of the two ATP-binding sites in ClpA, the ATPase component of protease Ti in Escherichia coli. 771 11

We have characterized a new ankyrin gene, expressed in brain and other tissues, that is subject to extensive tissue-specific alternative mRNA processing. The full-length polypeptide has a molecular mass of 480 kDa and includes a predicted globular head domain, with membrane- and spectrin-binding activities, as well as an extended "tail" domain. We term this gene ankyrinG based on its giant size and general expression. Two brain-specific isoforms of 480 kDa and 270 kDa were identified that contain a unique stretch of sequence highly enriched in serine and threonine residues immediately following the globular head domain. Antibodies against the serine-rich domain and spectrin-binding domain revealed labeling of nodes of Ranvier and axonal initial segments. Ankyrin-binding proteins also known to be localized in these specialized membrane domains include the voltage-dependent sodium channel, the sodium/potassium ATPase, sodium/calcium exchanger, and members of the neurofascin/L1 family of cell adhesion molecules. The neural-specific ankyrinG polypeptides are candidates to participate in maintenance/targeting of ion channels and cell adhesion molecules to nodes of Ranvier and axonal initial segments.
 ...
PMID:AnkyrinG. A new ankyrin gene with neural-specific isoforms localized at the axonal initial segment and node of Ranvier. 783 69

We isolated four azide-resistant secA mutants of Bacillus subtilis and found that all of them were the result of a single amino acid replacement of threonine 128 of SecA by alanine or isoleucine. In the presence of 1.5 mM sodium azide, cell growth and protein translocation of the wild-type strain were completely inhibited, but those of the azide-resistant mutant strains were not. Wild-type and two mutant SecA proteins were purified. Both the basal level and the elevated ATPase activity of the mutant SecA proteins were threefold higher than those of the wild-type SecA. The elevated ATPase activity of the SecA mutants was reduced upon the addition of 1.5 mM sodium azide by only 5-10% as compared with 40% for that of the wild-type. These results indicate that the elevated ATPase activity of the SecA mutants is resistant to sodium azide and that is also required for the protein translocation process of B. subtilis.
 ...
PMID:Acquisition of azide-resistance by elevated SecA ATPase activity confers azide-resistance upon cell growth and protein translocation in Bacillus subtilis. 789 2


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>