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)

Protein storage vacuoles were examined for the induction of H+-pyrophosphatase (H+-PPase), H+-ATPase, and a membrane integral protein of 23 kD after seed germination. Membranes of protein storage vacuoles were prepared from dry seeds and etiolated cotyledons of pumpkin (Cucurbita sp.). Membrane vesicles from etiolated cotyledons had ATP- and pyrophosphate-dependent H+-transport activities. H+-ATPase activity was sensitive to nitrate and bafilomycin, and H+-PPase activity was stimulated by potassium ion and inhibited by dicyclohexylcarbodiimide. The activities of both enzymes increased after seed germination. On immunoblot analysis, the 73-kD polypeptide of H+-PPase and the two major subunits, 68 and 57 kD, of vacuolar H+-ATPase were detected in the vacuolar membranes of cotyledons, and the levels of the subunits of enzymes increased parallel to those of enzyme activities. Small amounts of the subunits of the enzymes were detected in dry cotyledons. Immunocytochemical analysis of the cotyledonous cells with anti-H+-PPase showed the close association of H+-PPase to the membranes of protein storage vacuoles. In endosperms of castor bean (Ricinus communis), both enzymes and their subunits increased after germination. Furthermore, the vacuolar membranes from etiolated cotyledons of pumpkin had a polypeptide that cross-reacted with antibody against a 23-kD membrane protein of radish vacuole, VM23, but the membranes of dry cotyledons did not. The results from this study suggest that H+-ATPase, H+-PPase, and VM23 are expressed and accumulated in the membranes of protein storage vacuoles after seed germination. Overall, the findings indicate that the membranes of protein storage vacuoles are transformed into those of central vacuoles during the growth of seedlings.
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PMID:Accumulation of Vacuolar H+-Pyrophosphatase and H+-ATPase during Reformation of the Central Vacuole in Germinating Pumpkin Seeds. 1223 3

The effects of exogenously applied gibberellic acid (GA(3)) or brassinolide (BL) on the H(+)-pumps and aquaporin in the vacuolar membrane of rice seedling leaf sheath were investigated. Antibodies against mung bean H(+)-PPase, the B subunit of V-ATPase, and radish tonoplast intrinsic protein (TIP) cross-reacted with the vacuolar membrane proteins of rice seedling leaf sheath. The results of immunoblot analysis showed that the amounts of H(+)-PPase and V-ATPase were retained at a high level for two days in the presence of GA(3), although the level gradually decreased without phytohormones, indicating that GA(3) has a promotive effect on the activities of vacuolar H(+)-pumps. However, the levels of V-ATPase and H(+)-PPase were increased on day 2 and then decreased when treated with BL. There were no visible differences in the level of TIP upon treatment with GA(3) and BL. In comparison with the water control, the activity of H(+)-PPase treated with BL was also retained at a relatively high level, suggesting that BL has a stimulative effect on the activities of H(+)-PPase. These results indicate that GA(3) and BL might be involved in the regulation of the quantity and activities of plant vacuolar H(+)-pumps.
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PMID:Modulation of vacuolar H+ -pumps and aquaporin by phytohormones in rice seedling leaf sheaths. 1252 Jan 80

H(+)-pyrophosphatase (H(+)-PPase), which pumps H(+) across membranes coupled with PP(i) hydrolysis, is found in most plants, and some parasitic protists, eubacteria and archaebacteria. We assayed a number of extracts derived from 145 marine invertebrates as to their inhibitory effect on plant vacuolar H(+)-PPase. Acylspermidine derivatives [RCONH(CH(2))(3)N(CH(3))(CH(2))(4)N(CH(3))(2)] from a soft coral (Sinularia sp.) inhibited the PPi-hydrolysis activity of purified H(+)-PPase and the PP(i)-dependent H(+) pump activity (half inhibition concentration, 1 micro M) of vacuolar membranes of mung bean. The apparent K(i) was determined to be 0.9 micro M. Acylspermidines did not affect the activity of vacuolar H(+)-ATPase, plasma membrane H(+)-ATPase, mitochondrial ATPase or cytosolic PPase. Acylspermidines inhibited the acidification of vacuoles in protoplasts, as found on monitoring by the acridine orange fluorescent method. These results indicate that acylspermidine derivatives represent new inhibitors of H(+)-PPase with relatively high specificity.
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PMID:Acylspermidine derivatives isolated from a soft coral, Sinularia sp, inhibit plant vacuolar H(+)-pyrophosphatase. 1286 38

Schlesinger and Coon's report that crystalline yeast inorganic pyrophosphatase, in addition to its known ability to hydrolyze inorganic pyrophosphate in the presence of Mg ions, is also able to catalyze the hydrolysis of ATP and ADP in the presence of Zn ions was confirmed. A systematic study showed that the ratio of 370 of PPase-Mg over ATPase-Zn activities per milligram protein in various preparations of pyrophosphatase obtained in the course of isolation of crystalline pyrophosphatase from baker's yeast was nearly identical in all the preparations, independent of their purity. The course of hydrolysis of ATP by crystalline pyrophosphatase in the presence of Zn was carried out with the aid of ion exchange on Dowex 1. The finding of Schlesinger and Coon that the hydrolysis proceeds from ATP to ADP and then slowly to AMP was confirmed. The kinetics of the first phase of the reaction was found to depend on the molar ratio of Zn/ATP in the reaction mixture. Mg ions in the presence of Zn ions have an accelerating effect on the rate of hydrolysis of ATP. This suggests strongly that both activities-ATPase and PPase-are manifestations of the same active group in the protein molecule of crystalline pyrophosphatase.
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PMID:Hydrolysis of adenosine triphosphate by crystalline yeast pyrophosphatase. Effect of zinc and magnesium ions. 1446 May 83

The H+-PPase activity was characterized in membrane fractions of ovary and eggs of Rhodnius prolixus. This activity is totally dependent on Mg2+, independent of K+ and strongly inhibited by NaF, IDP and Ca2+. The membrane proteins of eggs were analyzed by western blot using antibodies to the H+-PPase from Arabidopsis thaliana. The immunostain was associated with a single 65-kDa polypeptide. This polypeptide was immunolocalized in yolk granule membranes by optical and transmission electron microscopy. We describe the acidification of yolk granules in the presence of PPi and ATP. This acidification is inhibited in the presence of NAF, Ca2+ and antibodies against H+-PPase. These data show for the first time in animal cells that acidification of yolk granules involves an H+-PPase as well as H+-ATPase.
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PMID:A new model for proton pumping in animal cells: the role of pyrophosphate. 1472 94

The gene of the previously described plasma-membrane-bound acidic pyrophosphatase (exo-PPase) and adjacent genes of the hyperthermoacidophilic crenarchaeon Sulfolobus acidocaldarius (DSM 639) were cloned and sequenced. The 4-kb gene cluster comprises four open reading frames (sepp, simp, sabc, and satr) encoding the pyrophosphatase, a small hydrophobic protein of unknown cellular function, a hydrophilic ABC transport ATPase, and an amino transferase. The four proteins have deduced molecular masses of 21, 16, 34, and 48 kDa, respectively. Sepp, simp, and sabc are transcribed as monocistronic mRNAs from which sepp and sabc have been heterologously expressed by in vitro translation using reticulocyte lysates. The Sulfolobus acidocaldarius acidic exo-pyrophosphatase is a membrane-residing protein anchored with five transmembrane alpha-helices. Alignments with protein sequences from databases together with predictions of membrane topology reveal a novel group of proteins with the conserved phosphatase motif KxxxxxRP-(x12-54)-PSGH-(x31-54)-SRxxxxxHxxxD. For none of them a phosphatase or pyrophosphatase activity has yet been described except for the authentic Sulfolobus acidocaldarius protein. On the basis of these investigations a direct role of the exo-PPase in dolichyl phosphate or pyrophosphate hydrolysis and in resistance to the peptide antibiotic bacitracin is discussed.
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PMID:Novel functional aspects of the membrane-bound exo-pyrophosphatase of the hyperthermoacidophilic archaeon Sulfolobus are provided by analysis of its gene and the adjacent gene cluster. 1516 18

The changes in ATP and PPi contents in roots under NaCl stress, and the effect of PPi on tonoplast H(+)-ATPase activity were studied with two barley cultivars differing in salt tolerance. The results showed that tonoplast H(+)-ATPase activity in salt-tolerant barley cultivar "Tanyin 2" roots increased obviously under NaCl 200 mmol/L (containing half-strength Hoagland solution) for 2 d, and decreased gradually. Tonoplast H(+)-PPase activity always decreased under NaCl stress. For salt-sensitive barley cultivar "Kepin 7", both tonoplast H(+)-ATPase and H(+)-PPase activities decreased during NaCl stress, as compared with control(grown in half-strength Hoagland solution), ATP content of "Tanyin 2" roots increased under NaCl stress for 2 d, and decreased on 4 d after NaCl stress, as compared with control. In "Kepin 7" roots, ATP accumulation was inhibited during NaCl stress. Pyrophosphate (PPi) content increased slightly both in "Tanyin 2" and "Kepin 7" roots under NaCl stress. Tonoplast H(+)-ATPase activity was inhibited competitively by PPi. These results indicated that the increase in rate of ATP accumulation might be essential for the stimulation of tonoplast H(+)-ATPase activity induced by NaCl. The decrease in ATP content and the inhibition of PPi might result in the decrease of tonoplast H(+)-ATPase activity in barley roots under NaCl stress.
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PMID:Tonoplast H+-ATPase activity in barley roots is regulated by ATP and pyrophosphate contents under NaCl stress. 1558 8

Seedlings of tomato (Lycopersicon esculentum Mill.) were grown in nutrient solution to investigate the changes in malondialdehyde (MDA) and proline content, and activities of antioxidative enzymes, plasmalemma H(+)-ATPase, and tonoplast H(+)-ATPase and H(+)-PPase to iso-osmotic stress of Ca(NO(3))(2) (80 mmol/L) and NaCl (120 mmol/L). The results indicated that both Ca(NO(3))(2) and NaCl stress significantly increased superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activities in leaf cytosols and chloroplasts. The extent of increase caused by NaCl was higher than that by Ca(NO(3))(2). The activities of SOD, CAT and APX in mitochondria were increased under Ca(NO(3))(2) stress and decreased under NaCl stress. Salt stress enhanced the activities of plasmalemma H(+)-ATPase, tonoplast H(+)-ATPase and H(+)-PPase. The increases in tonoplast H(+)-ATPase and H(+)-PPase activity were much higher under Ca(NO(3))(2) stress than under NaCl stress. The MDA and proline content increased under salt stress, especially under NaCl stress. From the results, it can be concluded that both salt inhibited the plant growth, the effect of NaCl being much heavier.
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PMID:[Effects of iso-osmotic salt stress on the activities of antioxidative enzymes, H+-ATPase and H+-PPase in tomato plants]. 1559 28

Intracellular pH homeostasis is a prerequisite for biological processes and requires the action of proton pumps. The vacuolar H(+)-ATPase (V-ATPase) is involved in regulating pH in endomembrane compartments of all eukaryotic cells. In plants, there is an additional endomembrane proton pump, H(+)-pyrophosphatase (H(+)-PPase). However, the relative roles of the two types of pumps in endomembrane acidification and energization of secondary active transport are unclear. Here, we show that a strong T-DNA insertion allele of VHA-A, the single copy gene encoding the catalytic subunit of the Arabidopsis V-ATPase, causes complete male and partial female gametophytic lethality. Severe changes in the morphology of Golgi stacks and Golgi-derived vesicles in male gametophytes are the first visible symptoms of cell degeneration leading to a failure to develop mature pollen. Similar effects on Golgi morphology were observed in pollen tubes when growth was blocked by Concanamycin A, a specific V-ATPase inhibitor. Taken together, our results suggests that V-ATPase function is essential for Golgi organization and development of the male gametophyte.
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PMID:Essential role of the V-ATPase in male gametophyte development. 1561 Mar 54

The petal color of morning glory, Ipomoea tricolor cv. Heavenly Blue, changes from purplish red to blue during flower opening. This color change is caused by an unusual increase in vacuolar pH from 6.6 to 7.7 in the colored adaxial and abaxial cells. To clarify the mechanism underlying the alkalization of epidermal vacuoles in the open petals, we focused on vacuolar H+-ATPase (V-ATPase), H+-pyrophosphatase (V-PPase) and an isoform of Na+/H+ exchanger (NHX1). We isolated red and blue protoplasts from the petals in bud and fully open flower, respectively, and purified vacuolar membranes. The membranes contained V-ATPase, V-PPase and NHX1, which were immunochemically detected, with relatively high transport activity. NHX1 could be detected only in the vacuolar membranes prepared from flower petals and its protein level was the highest in the colored petal epidermis of the open flower. These results suggest that the increase of vacuolar pH in the petals during flower opening is due to active transport of Na+ and/or K+ from the cytosol into vacuoles through a sodium- or potassium-driven Na+(K+)/H+ exchanger NXH1 and that V-PPase and V-ATPase may prevent the over-alkalization. This systematic ion transport maintains the weakly alkaline vacuolar pH, producing the sky-blue petals.
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PMID:The involvement of tonoplast proton pumps and Na+(K+)/H+ exchangers in the change of petal color during flower opening of Morning Glory, Ipomoea tricolor cv. Heavenly Blue. 1569 44


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