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)

Isolated mitochondria of Saccharomyces cerevisiae possess polyphosphatases insensitive to a number of inhibitors of ATPase and pyrophosphatase of the same organelles and differing from the last two by neutral pH optima and molecular masses. After subfractionation of mitochondria, the polyphosphatase activity is distributed among the membrane and soluble preparations. The membrane-bound and soluble polyphosphatase activities are represented by different enzymes distinguished by molecular masses, substrate specificity, Km values, and relation to mono- and divalent cations. The membrane-bound polyphosphatases have molecular masses of 120 and 76 kDa, and the soluble one of about 36 kDa. All three enzymes appear to have a monomeric structure. The soluble polyphosphatase activity is stimulated by divalent cations in contrast to the membrane-bound one which is inhibited by the same cations, including Mg2+. Monovalent cations do not actually change the activity of the soluble enzyme, but stimulate it in the membrane preparation. Specific activities for the hydrolysis of polyphosphates with average chain lengths of 9-188 phosphate residues increase under increasing degree of substrate polymerization in the membrane preparation and are actually unchanged in the soluble one. The affinity of the soluble enzyme to polyphosphates is 5-10 times higher than that of the membrane-bound polyphosphatases.
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PMID:Membrane-bound and soluble polyphosphatases of mitochondria of Saccharomyces cerevisiae: identification and comparative characterization. 967 65

Little is known about the development of the central nervous system (CNS) in humans. Ethical considerations preclude experimental studies in this field, and as a result most available data on human ontogenesis are descriptive. Comparative anatomic and embryologic studies have demonstrated that the main developmental milestones are conserved across species, and their results can be used to suggest a likely scenario for human development. The development of the ventricles, meninges, and choroid plexuses are discussed in this article. The central cavity of the neural tube is formed during neurulation, which occurs during the fourth gestational week. The first milestone is occlusion of the spinal neurocele (the central canal in the neural tube) shortly after neurulation. This prevents free communication between the ventricular system and the amniotic cavity. The second milestone is development of the meninges, which separate the central nervous system from the rest of the body. The embryonic origin of the meninges varies across species. In birds (and probably in mammals), the spinal meninges are derived from the somitic mesoderm, the brainstem meninges from the cephalic mesoderm, and the telencephalic meninges from the neural crest. Differentiation of the meninges, which involves formation of the subarachnoid space, occurs early, before the cerebrospinal fluid (CSF) begins to flow around the CNS. During ontogenesis, the meninges play a key role in regulating the growth of underlying nervous structures. They induce the formation of the superficial glial limiting layer and stimulate the growth of precursors located in the superficial blastemas of the cerebellum and hippocampus. The choroid plexuses are complex specialized structures that produce most of the CSF. Their epithelium derives from the neural tube epithelium and their mesenchyma from the meninges. Of the many enzymes produced in the choroid plexuses, some reflect the pivotal metabolic role of these structures (alkaline and acid phosphatases, magnesium-dependent ATPase, glucose-6-phosphatase, thiamine pyrophosphatase, adenylate cyclase, oxidoreductase, esterases, hydrolases, cathepsin D, and glutathion S-transferase). The two enzymes that are crucial to the production of CSF are Na+/K+ ATPase and carbonic anhydrase. Inactivation of catecholamines is mediated by catechol-O-methyltransferase and by the monoamine oxidases A and B. The morphology and synthesis profile of the choroid plexuses changes during development, although little is known about these changes in humans.
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PMID:Embryonic and fetal development of structures associated with the cerebro-spinal fluid in man and other species. Part I: The ventricular system, meninges and choroid plexuses. 975 71

The Drosophila nucleosome remodeling factor (NURF) is a protein complex consisting of four polypeptides that facilitates the perturbation of chromatin structure in vitro in an ATP-dependent manner. The 140-kD NURF subunit, imitation switch (ISWI), is related to the SWI2/SNF2 ATPase. Another subunit, NURF-55, is a 55-kD WD repeat protein homologous to the human retinoblastoma-associated protein RbAp48. Here, we report the cloning and characterization of the smallest (38 kD) component of NURF. NURF-38 is strikingly homologous to known inorganic pyrophosphatases. Both recombinant NURF-38 alone and the purified NURF complex are shown to have inorganic pyrophosphatase activity. Inhibition of the pyrophosphatase activity of NURF with sodium fluoride has no significant effect on chromatin remodeling, indicating that these two activities may be biochemically uncoupled. Our results suggest that NURF-38 may serve a structural or regulatory role in the complex. Alternatively, because accumulation of unhydrolyzed pyrophosphate during nucleotide incorporation inhibits polymerization, NURF may also have been adapted to deliver pyrophosphatase to chromatin to assist in replication or transcription by efficient removal of the inhibitory metabolite.
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PMID:Inorganic pyrophosphatase is a component of the Drosophila nucleosome remodeling factor complex. 978 95

Using a polyclonal antiserum specific for the tonoplastic H(+)-pyrophosphatase (tPPase), significant amounts of antigenic polypeptides of the correct molecular mass were detected in Western blots of plasma membrane isolated from cauliflower (Brassica oleracea L.) inflorescence by phase-partitioning and subsequent sucrose density centrifugation. Potassium iodide-stripped plasma membranes continued to give a strong positive signal, indicating that the PPase antigen detected was not a result of contamination through soluble PPase released during homogenisation. The same preparation contained negligible vacuolar (v)H(+)-ATPase activity and the A subunit of the vATPase could not be detected by immunoblotting. Plasma membrane fractions exhibited a proton-pumping activity with ATP as substrate, but such an activity was not measurable with pyrophosphate, although the hydrolysis of this substrate was recorded. By contrast, pyrophosphate supported proton pumping in tonoplast-containing fractions. Immunogold electron microscopy confirmed the presence of PPase at the plasma membrane as well as at the tonoplast, trans Golgi network, and multivesicular bodies. The density of immunogold label was higher at the plasma membrane than at the tonoplast, except for membrane fragments occurring in the lumen of the vacuoles which stained very conspicuously.
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PMID:Localization of pyrophosphatase in membranes of cauliflower inflorescence cells. 1033 84

Inorganic pyrophosphate promoted the acidification of an intracellular compartment in permeabilized promastigotes of Leishmania donovani, as measured by Acridine Orange uptake. The proton gradient generated by pyrophosphate was collapsed by addition of nigericin or NH4Cl. Pyrophosphate-driven proton translocation was stimulated by potassium ions, and inhibited by NaF, the pyrophosphate analogues imidodiphosphate and aminomethylenediphosphonate (AMDP), dicyclohexylcarbodiimide, and the thiol reagents p-hydroxymercuribenzoate and N-ethylmaleimide, all at concentrations similar to those that inhibit the plant vacuolar proton-pumping pyrophosphatase (H+-PPase). The proton translocation activity had a pH optimum in the range 7.0-7.5, and was unaffected by bafilomycin A1 (40 nM), concanamycin A (5 nM), sodium o-vanadate (500 microM) and KNO3 (200 mM). AMDP-sensitive pyrophosphate hydrolysis was also detected in promastigotes, and potassium ions also stimulated this activity. Sodium ions disrupted pH gradients established in the presence of ATP but not in the presence of pyrophosphate, and sequential addition of ATP and pyrophosphate resulted in partially additive Acridine Orange accumulation, suggesting that the vacuolar H+-PPase is in a different intracellular compartment from the vacuolar H+-ATPase and Na+/H+ exchanger of L. donovani promastigotes. Separation of promastigote extracts on Percoll gradients yielded a dense fraction that contained H+-PPase activity but lacked ATPase activity and markers for mitochondria, glycosomes and lysosomes. The organelles in this fraction appeared by electron microscopy to consist of electron-dense vacuoles. In summary, these results indicate that, in contrast to plant vacuoles, vacuolar H+-PPase and vacuolar ATPase activities are present in different compartments in L. donovani promastigotes.
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PMID:Presence of a vacuolar H+-pyrophosphatase in promastigotes of Leishmania donovani and its localization to a different compartment from the vacuolar H+-ATPase. 1035 62

P-type ATPases such as the Na+,K+-ATPase (sodium pump) hydrolyze ATP to pump ions through biological membranes against their electrochemical gradients. The mechanisms that couple ATP hydrolysis to the vectorial ion transport are not yet understood, but unveiling structures that participate in ATP binding and in the formation of the ionophore might help to gain insight into this process. Looking at the alpha- and beta-phosphates of ATP as a pyrophosphate molecule, we found that peptides highly conserved among all soluble inorganic pyrophosphatases are also present in ion-transporting ATPases. Included therein are Glu48 and Lys56 of the Saccharomyces cerevisiae pyrophosphatase (SCE1-PPase) that are essential for the activity of this enzyme and have been shown in crystallographic analysis to interact with phosphate molecules. To test the hypothesis that equivalent amino acids are also essential for the activity of ion-transporting ATPases, Glu472 and Lys480 of the sodium pump alpha 1 subunit corresponding to Glu48 and Lys56 of SCE1-PPase were mutated to various amino acids. Mutants of the sodium pump alpha1 subunit were expressed in yeast and analyzed for their ATPase activity and their ability to bind ouabain in the presence of either ATP, Mg2+, and Na+ or phosphate and Mg2+. All four mutants investigated, Glu472Ala, Glu472Asp, Lys480Ala, and Lys480Arg, display only a fraction of the ATPase activity obtained with the wild-type enzyme. The same applies with respect to their ability to bind ouabain, where maximum ouabain binding to the mutants accounts for only about 10% of the binding obtained with the wild-type enzyme. On the basis of our results, we conclude that Glu472 and Lys480 are essential for the activity of the sodium pump. Their function is probably to arrest the alpha- and beta-phosphate groups of ATP in a proper position prior to hydrolysis of the gamma-phosphate group. The identification of these amino acids as essential components of the ATP-recognizing mechanism of the pump has resulted in a testable hypothesis for the initial interactions of the sodium pump, and possibly of other P-type ATPases, with ATP.
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PMID:Glutamic acid 472 and lysine 480 of the sodium pump alpha 1 subunit are essential for activity. Their conservation in pyrophosphatases suggests their involvement in recognition of ATP phosphates. 1041 94

Inorganic pyrophosphate promoted the acidification of an intracellular compartment in permeabilized procyclic trypomastigotes of Trypanosoma brucei, as measured by acridine orange uptake. The proton gradient generated by pyrophosphate was collapsed by addition of nigericin or NH(4)Cl. Pyrophosphate-driven proton translocation was stimulated by potassium ions and inhibited by KF, by the pyrophosphate analogs imidodiphosphate and aminomethylenediphosphonate (AMDP), and by the thiol reagent p-hydroxymercuribenzoate at concentrations similar to those that inhibit the plant vacuolar H(+)-pyrophosphatase (PPase). The proton translocation activity had a pH optimum around 7.5 and was partially inhibited by 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (10 microM) and unaffected by bafilomycin A(1) (40 nM), concanamycin A (5 nM), sodium o-vanadate (500 microM), oligomycin (1 microM), N-ethylmaleimide (100 microM), and KNO(3). AMDP-sensitive pyrophosphate hydrolysis was detected in both procyclic and bloodstream trypomastigotes. Measurements of acridine orange uptake in permeabilized procyclic trypomastigotes in the presence of different substrates and inhibitors suggested the presence of H(+)-ATPase, H(+)-PPase, and (ADP-dependent) H(+)/Na(+) antiport activity in the same compartment. Separation of bloodstream and procyclic trypomastigote extracts on Percoll gradients yielded fractions that contained H(+)-PPase (both stages) and H(+)/Na(+) exchanger (procyclics) activities but lacked markers for mitochondria, glycosomes, and lysosomes. The organelles in these fractions were identified by electron microscopy and X-ray microanalysis as acidocalcisomes (electron-dense vacuoles). These results provide further evidence for the unique nature of acidocalcisomes in comparison with other, previously described, organelles.
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PMID:Characterization of a vacuolar pyrophosphatase in Trypanosoma brucei and its localization to acidocalcisomes. 1052 60

Ultrastructural and light microscopic cytochemical methods were used to study the distribution and changes in distribution of three phosphatase enzymes: 5'-nucleotidase (5N); thiamine pyrophosphatase (TPP); and adenosine triphosphatase (ATP) in the rat endometrium during early pregnancy up to the time of blastocyst attachment. The authors were particularly interested in changes in the apical plasma membrane and reaction product for all three enzymes was clearly localized along this membrane especially on day 1 of pregnancy. However, the three enzymes showed markedly different patterns of organization of reaction product at later times during early pregnancy. 5N, while showing a continuous lining along the microvilli on day 1 was virtually undetectable by day 6. TPP was also strongly present apically on day 1, but reaction product was not always found as a continuous lining. Again, by day 6, there was no presence of this enzyme along the apical surface. ATP differed from the other two in that it produced a strong, and relatively unchanged reaction product along the apical plasma membrane from day 1 through to day 6 of pregnancy. The changes in distribution of these enzymes was particularly obvious at the electron microscopic level and we consider their contribution to the process of 'plasma membrane transformation' of early pregnancy.
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PMID:Differential alterations in the distribution of three phosphatase enzymes during the plasma membrane transformation of uterine epithelial cells in the rat. 1052 45

Arabidopsis thaliana vacuolar H(+)-translocating pyrophosphatase (V-PPase) was expressed functionally in yeast vacuoles with endogenous vacuolar H(+)-ATPase (V-ATPase), and the regulation and reversibility of V-ATPase were studied using these vacuoles. Analysis of electrochemical proton gradient (DeltamuH) formation with ATP and pyrophosphate indicated that the proton transport by V-ATPase or V-PPase is not regulated strictly by the proton chemical gradient (DeltapH). On the other hand, vacuolar membranes may have a regulatory mechanism for maintaining a constant membrane potential (DeltaPsi). Chimeric vacuolar membranes showed ATP synthesis coupled with DeltamuH established by V-PPase. The ATP synthesis was sensitive to bafilomycin A(1) and exhibited two apparent K(m) values for ADP. These results indicate that V-ATPase is a reversible enzyme. The ATP synthesis was not observed in the presence of nigericin, which dissipates DeltapH but not DeltaPsi, suggesting that DeltapH is essential for ATP synthesis.
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PMID:Regulation and reversibility of vacuolar H(+)-ATPase. 1061 29

Submandibular glands obtained post-mortem from mature ferrets of both sexes were examined with the use of light microscopical histochemical methods for proteins, mucosubstances and enzymes associated with cell functions or organelles. Demilunar cells showed carboxylated mucosubstances that were mainly non-sulphated, and diffuse activity for peroxidase, E600-sensitive esterase and acid phosphatase. Thiol groups were also detected in these cells. Central acinar cells showed sulphated mucosubstances, disulphides and reticular staining for thiamine pyrophosphatase. Intercalary ducts showed diffuse activity for NADH and NAD(P)H dehydrogenases. Striated ducts contained protein, tryptophan, disulphides, neutral mucosubstances and E600-sensitive esterase periluminally. Basally, the striated ductal cells showed variable activity for peroxidase, cytochrome oxidase, succinate dehydrogenase and acid phosphatase. Basolateral plasma membranes of these cells exhibited ouabain-sensitive Na,K-ATPase activity. The collecting ducts were characterized by variable periluminal staining for acid phosphatase, beta-glucuronidase, acid beta-galactosidase and E600-resistant esterase. The results suggest that the histological appearances of the acini of the submandibular gland of the ferret are dependent on the synthesis of secretory acid glycoproteins, that the striated ducts are involved with the secretion of tryptophan-rich product comprising neutral glycoproteins and showing esterase activity and with marked transport of ions and that the collecting ducts are involved with absorption.
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PMID:Morphological phenotypes and functional capabilities of submandibular parenchymal cells of the ferret investigated by protein, mucosubstance and enzyme histochemistry. 1066 22


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