K+-stimulated adenosine triphosphatase of maize roots: partial purification and inhibition by Helminthosporium maydis race T toxin

Tipton, Charles M.; Mondal, Mohammad H.; Benson, Michael J.

doi:10.1016/0048-4059(75)90032-6

Cited by 16 publications

(3 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Assays for K+-stimulated ATPase activity were carried out as described by Tipton et aL (26). The reaction mixture routinely contained 0.75 ,umol Bis-Tris buffer (pH 6.6), 50 ,l or 100 id of enzyme solution in a total volume of 1 ml.…”

Section: Methodsmentioning

confidence: 99%

“…The similar inhibition of hydrolysis of ATP and ADP by each of the analogs argues for the presence of both K+-ATPase and K+-ADPase activity on the same enzyme. Using the same assay system as described in Table VIII, assays were run to determine the effects of an inhibitor of myokinase activity, p',p5-di(adenosine-5'-)pentaphosphate [A(P)6AJ, (19,26).…”

Section: Purification Of Cation-atpase From Cornmentioning

confidence: 99%

See 1 more Smart Citation

Purification and Characterization of a Cation-stimulated Adenosine Triphosphatase from Corn Roots

Benson¹,

Tipton²

1978

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

Section: Methodsmentioning

confidence: 99%

Section: Purification Of Cation-atpase From Cornmentioning

confidence: 99%

Purification and Characterization of a Cation-stimulated Adenosine Triphosphatase from Corn Roots

Benson¹,

Tipton²

1978

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

“…Oligomycin is an inhibitor of mitochondrial ATPase activity (Bowman et al 1980) but it failed to inhibit ATPase in any preparation used in this study. Ophiobolin A is a fungal toxin from H. maydis which inhibits K+-stimulated ATPase from maize roots (Tipton et al 1975). It inhibited sugar transport in sugarcane by 36% (Komor et al 1982), but there was only slight inhibition of sugarcane ATPase by this toxin.…”

Section: Effect Of Inhibitors and Ionophores On Atpase Activitymentioning

confidence: 99%

Characteristics of ATPase from sugarcane protoplast and vacuole membranes

Thom

Willenbrink

Maretzki

1983

Physiologia Plantarum

View full text Add to dashboard Cite

Characteristics of membrane‐associated ATPase from commercial Hawaiian varieties of sugarcane (Saccharum spp. hybrids) were investigated in preparations from sugarcane cell suspension culture and from stalk tissues of the intact plant. In order to examine comparable preparations, protoplasts and vacuoles, in turn, were obtained from both sources. ATPase from preparations of crude protoplast membranes and tonoplast had a pH optimum of 6 to 6.5. The relative effectiveness of divalent cations in stimulating ATPase was Mg2+ > Mn2+≥ Co2+ > Ca2+≥ Zn2+. Enzyme activity was not stimulated by K+, nor by other monovalent cations. Protoplasts and vacuoles from both sources showed significant acid phosphatase activity. Acid phosphatase activity was inhibited by molybdate, but ATPase activity was unaffected. Membrane preparations from protoplasts contained inorganic pyrophosphatase, but enzyme activity was low or not present in tonoplast preparations. Cell suspension and stalk tissue preparations hydrolyzed a large number of nucleoside di‐ and triphosphates. The hydrolysis is most likely due to a series of enzymes rather than a single enzyme. ATPase from protoplast and tonoplast preparations was inhibited 30–50% by diethylstilbestrol and sodium ortho‐vanadate and was unaffected by ionophores. This study illustrates the complexity of phosphohydrolase activities in membrane preparations from sugarcane. The study, however, also illustrates substantial similarity in the behavior of these enzymes, whether they are derived from the plant itself or from cell cultures originating from comparable tissues of the plant.

show abstract

The mechanism of sugar uptake by sugarcane suspension cells

Komor

Thom

Maretzki

1981

Planta

View full text Add to dashboard Cite

Sugarcane cell suspensions took up sugar from the medium at rates comparable to or greater than sugarcane tissue slices or plants in the field. This system offers an opportunity for the study of kinetic and energetic mechanisms of sugar transport in storage parenchyma-like cells in the absence of heterogeneity introduced by tissues. The following results were obtained: (a) The sugar uptake system was specific for hexoses; as previously proposed, sucrose was hydrolyzed by an extracellular invertase before the sugar moieties were taken up; no evidence for multiple sugar uptake systems was obtained. - (b) Uptake of the glucose-analog 3-O-methylglucose (3-OMG) reached a plateau value with an intracellular concentration higher than in the medium (approximately 15-fold). - (c) There was a balance of influx and efflux during steady state; the rate of exchange influx was lower than the rate of net influx; the Km value was higher (70 μM) than for net influx (24 μM); the exchange efflux is proposed to be mediated by the same transport system with a Km value of approximately 2.6 mM for internal 3-OMG; the rate of net efflux of hexoses was less than a third of the rate of exchange efflux. - (d) The uptake of hexoses proceeded as proton-symport with a stoichiometry of 0.87 H(+) per sugar; during the onset of hexose transport there was a K(+) exit of 0.94 K(+) per sugar for charge compensation. (It was assumed that the "real" stoichiometries are 1 H(+) and 1 K(+) per sugar.) The Km values for sugar transport and sugar-induced proton uptake were identical. Sucrose induced proton uptake only in the presence of cell wall invertase. - (e) There was no net proton uptake with 3-OMG by cells which were preloaded with glucose though there was significant sugar uptake. It is assumed, therefore, that the exit of hexose occurs together with protons. - (f) The protonmotive potential of sugarcane cells corresponded to about 120 mV: pH-gradient 1.1 units, membrane potential of-60 mV (these values increased if vacuolar pH and membrane potential were also considered). It was abolished by uncouplers, and the magnitude of the components depended on the external pH value. We present evidence for the operation of a proton-coupled sugar transport system in cell suspensions that were derived from, and have characteristics of, storage parenchyma. The quantitative rates of sugar transport suggest that the role of this transport system is not limiting for sugar storage.

show abstract

K+-stimulated adenosine triphosphatase of maize roots: partial purification and inhibition by Helminthosporium maydis race T toxin

Cited by 16 publications

References 21 publications

Purification and Characterization of a Cation-stimulated Adenosine Triphosphatase from Corn Roots

Purification and Characterization of a Cation-stimulated Adenosine Triphosphatase from Corn Roots

Characteristics of ATPase from sugarcane protoplast and vacuole membranes

The mechanism of sugar uptake by sugarcane suspension cells

Contact Info

Product

Resources

About