H+-ATPase activity

Z. Varanini, R. Pinton, M. G. De Biasi, S. Astolfi, and A. Maggioni, Low molecular weight humic substances stimulate H -ATPase activity of plasma membrane vesicles isolated from oat (Avena sativa L.) roots. Plant Soil I53 6 (1993). 

I. H+-ATPase, H+-PPase, and UDPase. Enzyme activities of vanadate- or nitrate-sensitive H+-ATPase, H+-PPase, and UDPase are measured by the quantitation of released inorganic phosphate from the substrate by enzymatic hydrolyzation. When H+-ATPase activities are assayed, at least three substrate mixtures should be prepared (1) a substrate mixture containing nitrate, (2) a substrate mixture containing vanadate, and... 

Neural membranes isolated from primary astrocyte cultures established from newborn Sprague-Dawley rat cerebella were exposed to 3, 6 or 9 mmol/L ethylbenzene for 1 h. ATPase activity decreased linearly with log concentration of ethylbenzene (Naskali et al., 1994). In the same astrocyte cultures, ethylbenzene (3, 6 or 9 mmol/L 1-h exposure) decreased in a dose-dependent manner the activity of important membrane integral proteins such as NaVK+-ATPase and Mg -ATPase (Vaalavirta Tahti, 1995). 

Other evidence is reported in the paper of Canellas et al. (2002), in which a stimulation of the plasma membrane H+-ATPase activity took place, apparently associated with an ability to promote expression of this enzyme, as confirmed by western blot analysis. Using antibodies raised against H+- ATPase PMA2 isoform from Nicotianaplumbaginifolia Viv. (Morsomme et al., 1996), it was discovered that the amount of immunoreactive protein at the PM A locus (approximately 96 kD) increased almost threefold in the membrane vesicles isolated from maize roots treated with HA. 

Canellas, L. P., Olivares, E L., Okorokova-Faqanha, A. L., and Faqanha, A. R. (2002). Humic acids isolated from earthworm compost enhance root elongation, lateral root emergence, and plasma membrane H+-ATPase activity in maize roots. Plant Physiol. 130, 1951-1957. 

Cruz-Ortega, R., Anaya, A. L., Gavilanes-Ruiz, M., Sanchez-Nieto, S., and Jimenez-Estrada, M. 1990. Effect of diacetyl piquerol on the H+-ATPase activity of microsomes from Ipomoea purpurea. J. Chem. Ecol. 16, 2253-2261... 

Doerrler, W.T., Raetz, C.R.H. ATPase activity of the MsbA lipid flippase of Escherichia coli. J Biol Chem 277 (2002) 36697-36705. 

In certain human pathologies, as well as in experimental animals, aluminum has been observed to accumulate preferentially inside lysosomes. The experimental evidence raised the possibility that lysosomes serve as an elective site of metal accumulation. Lysosomes might thus protect the rest of the cell from toxic effects produced by free metals or metal compounds. As reported by Zatta et al. [39] aluminum is able to inhibit the lysosomal H+ ATPase activity from rat liver. Intralysosomal pH is acidic, and it is accepted that it is maintained by the proton pump which is an enzyme activated by... 

Aguilera, R, Peinado, R.A., Millan, C., Ortega, J.M., Mauricio, J.C. (2006). Relationship between ethanol tolerance, H+-ATPase activity and the lipid composition of the plasma membrane in different wine yeast strains. Int. J. Food Microbiol., 110, 34-42. 

Ahn, S.J., Sivaguru, M., Osawa, H., Chung, G.C., Matsumoto, H., 2001. Aluminum inhibits the H -ATPase activity by permanently altering the plasma membrane surface potentials in squash roots. Plant Physiol.126, 1381-1390. 

Some studies have been carried out on the role of phosphorylated intermediates and the role of partial reactions, subunit structure and involvement of phospholipids. All these studies have been done with crude preparations from gastric mucosa, which means that the preparation contains (K -I- H )-ATPase activity (see Section 3). This makes it difficult to relate these findings to the anion-sensitive ATPase. 

Upon purification, the K -stimulated phosphatase activity is always copurified with the (K )-ATPase activity [63-65]. Mitochondrial markers, such as cytochrome c oxidase, succinate dehydrogenase, monoamino-oxidase, and the ribo-somal marker RNA are largely removed by the purification procedure. The same is true for the anion-sensitive ATPase and 5 nucleotidase activities, but some (Na — K )-ATPase activity is still present in highly purified (K" -I-H )-ATPase preparations. Purification is also characterised by a lowering of the K -insensitive Mg ATPase activity, but even in the purest preparations some Mg -ATPase activity (4% of (K -I- H )-ATPase activity) is still present. This may represent an impurity or an inherent property of the enzyme. 

The rate of phosphorylation is much faster than the overall turnover rate of the enzyme, suggesting that the phosphorylation step is not rate-limiting [71], Surprisingly, Wallmark and Mirdh [74] found that at low substrate concentration (5 /rM ATP) Na" decreases the rate of phosphorylation, the steady-state level of phosphorylation and the (K" -l-H )-ATPase activity. In the absence of, Na+ has a stimulating effect on the ATPase activity at this ATP concentration. Since at ATP concentrations normally used in the ATPase assay (1-5 mM) Na does not affect the ATPase activity, these findings are difficult to interpret. 

As previously discovered [52], the enzyme shows a cation-stimulated phosphatase activity, the cation specificity of which is the same as that of the ATPase and which is copurified with the enzyme [63]. The specific activity of the phosphatase reaction is 60-80% of that of the (K + H )-ATPase activity [63,77,78]. This is much higher than for (Na + K )-ATPase, where the activity of the phosphatase activity is only 10-20% of the ATPase activity [1]. 

Strong evidence for this assumption has been provided by Sachs and coworkers [58,66,78,87]. They found that the rate of proton uptake depends on the nature of the cation present and that the sequence of the stimulating effect of these cations is the same as for the ATPase reaction. The only exception is T1, which strongly stimulates the ATPase but inhibits proton transport [71]. The substrate specificity for the proton transport is also the same as for the (K +H" )-ATPase activity. Most inhibitors of the enzyme reaction, described in Section 3g, also inhibit the proton transport process. 

The herbicidal mode of action of benzoxazinoids is unknown. Sanchez-Moreiras et al. [127] reviewed what was known of the mode of action of BOA up until about 2003. BOA can inhibit mitochondrial function by interfering with both electron transport and mitochondrial ATPase activity [128]. A correlation between inhibition of plasma membrane H " -ATPase activity and inhibition of growth by BOA and DIBOA [129], suggests that their effects on nutrient uptake and electrolyte leakage could be caused by this primary effect [130]. BOA reduces the number of dividing meristematic... 

Hejl, A.M. and Koster, K.L. (2004) Juglone disrupts root plasma membrane H+-ATPase activity and impairs water uptake, root respiration, and growth in soybean (Glycine max and com (Zea mays). J. Chem. Ecol. 30, 453-171... 

Wallmark B, Larsson H, Humble L (1985) The relationship between gastric acid secretion and gastric H, ATPase activity. J Biol Chem 260 13681-13684... 

On the other hand, H transport in sealed microsome vesicles from high oleic acid cotyledons was stimulated compared to the normal genotype, while vanadate-sensitive H" -ATPase activity, responsible for H pumping, was not significantly different in both membranes (Table 3). This table also shows that... 

Palmgren MG. Regulation of plant plasma membrane H -ATPase activity. Physiol Plant 1991 83 314-23. 

Kasamo K. Inhibition of tonoplast and plasma mambrane H -ATPase activity in rice (Orvza sativa L.) culture cells by local anesthetics.Plant Cell Physiol. 1988 29 215-222. 

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