Studies on the Reaction Mechanism and Transport Function of P-type ATPases Associated with the Plant Plasma Membrane

Briskin, Donald P.; Basu, Swati; Ho, InSun

doi:10.1007/978-1-4615-3442-6_2

Cited by 4 publications

(2 citation statements)

References 45 publications

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“…^--Our results are relevant to another area of controversy concerning the existence of a Ca-*/H* antiporter in the PM (Shumaker andSze 1986, Kasai andMuto 1990). The more versatile substrate range of nucleotides hydrolysed by the Ca-*-pump, in comparison with the H*-ATPase (Briskin et al 1992), provides an opportunity to assess the importance of a ApH across the vesicles as a component of the observed Ca^"^ transport. In parallel experiments, we compared the effectiveness of GTP with ATP for driving Ca^* transport and, at the same time, monitored proton pumping.…”

Section: Discussionmentioning

confidence: 64%

Calcium transport across plasma membrane vesicles isolated from shoots of Stellaria media and Avena sativa

Ramón¹,

Cooke²,

Clarkson³

1993

Physiol Plant

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1993. Calcium transport across plasma membrane vesicles isolated from shoots of Stellaria media and Avena sativa. -Physiol. Plant. 89: 731-740.Plasma membrane vesicles (ca 40% inside-out, after one freeze-thaw cycle) were extracted and purified from the shoots of oat (Avena sativa L.) and chickweed (Stellaria media L ) using the two-phase aqueous polymer technique. In the presence of ATP or GTP a rapid uptake of -^' Ca^^ occurred (0.77 and 0.62 nmol Ca-+ mg' protein, for ATP and GTP, respectively, in oat, and 0.53 and 0.51 nmol Ca-+ mg"' protein, for ATP and GTP respectively, in chickweed). Nucleotide-dependent Ca-^-transport was sensitive to 1 [xM Erythrosin B (with ATP, inhibited by 52% in oat and in chickweed by 72%; with GTP inhibition was similar in both species at ca 67%); ATP-dependent uptake was greater in oat than in chickweed, but not stimulated by calmodulin. Addition of the calcium ionophore A-23187 resulted in the release of label from the vesicles (41% and 63% release with ATP and 24% and 52% release with GTP, in oat and chickweed, respectively). The results obtained suggest that Ca^^-transport is independent of the proton pump. In oat, kinetic data indicate a discontinuity m the absorption isotherm at 10 | JLM free calcium.

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Section: Discussionmentioning

confidence: 64%

Calcium transport across plasma membrane vesicles isolated from shoots of Stellaria media and Avena sativa

Ramón¹,

Cooke²,

Clarkson³

1993

Physiol Plant

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“…V-type ATPases have only been functionally identified as H*-pumps (Forgac 1989). P-type ATPases are characterised by having a phosphorylated aspartate intermediate, to cycle between E| and Ei forms, and are inhibited by vanadate (Briskin et al 1992). The plasma membrane H*-ATPase is a P-type enzyme and exists as a functional dimer ( = 200 kDa) (Briskm et al 1992) which is Mg-*-dependent and is further stimulated by K*.…”

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confidence: 99%

Characterisation of a Ca²⁺‐dependent ATP hydrolysis associated with the vacuolar membrane of wheat roots

Allen

Morais

Muir³

et al. 1995

Physiologia Plantarum

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Microsomal fractions from wheat tissues exhibit a higher level of ATP hydrolytic activity in the presence of Ca2+ than Mg2+. Here we characterise the Ca2+‐dependent activity from roots of Triticum aestivum lev. Troy) and investigate its possible function. Ca2+‐dependent ATP hydrolysis in the microsomal fraction occurs over a wide pH range with two slight optima at pH 5.5 and 7.5. At these pHs the activity co‐migrates with the major peak of nitrate‐inhibited Mg2+. Cl‐ATPase on continuous sucrose gradients indicating that it is associated with the vacuolar membrane. Ca2+‐dependent ATP hydrolysis can be distinguished from an inhibitory effect of Ca2+ on the plasma membrane K+, Mg2+‐ATPase following microsomal membrane separation using aqueous polymer two phase partitioning. The Ca2+‐dependent activity is stimulated by free Ca2+ with a Km of 8.1 μM in the absence of Mg2+ ([CaATP] = 0.8 mM). Vacuoiar membrane vacuolar preparations contain a higher Ca2+‐dependent than Mg2+‐dependent ATP hydrolysis, although the two activities are not directly additive. The nucleotide specificity of the divalent ion‐dependent activities in vacuolar membrane‐enriched fractions was low. hydrolysis of CTP and UTP being greater than ATP hydrolysis with both Ca2+ and Mg2+ The Ca2+‐dependent activity did discriminate against dinucleotides, and mononucleotides. and failed to hydrolyse phosphatase substrates. Despite low nucleotide specificity the Mg2+‐dependent activity functioned as a bafilomycin sensitive H+‐pump in vacuolar membrane vesicles. Ca2+‐dependent ATP hydrolysis was not inhibited by the V‐, P‐, or F‐type ATPase inhibitors bafilomycin. vanadate and azide, respectively. nor by the phosphatase inhibitor molybdate, but was inhibited 20% at pH 7.5 by K+. Possible functions of Ca2+‐dependent hydrolysis as a H+‐pump or a Ca2+‐pump was investigated using vacuolar membrane vesicles. No H+ or Ca2+ translocating activity was observed under conditions when the Ca2+‐dependent ATP hydrolysis was active.

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Membranes and Transport Systems in Plants: An Overview

Briskin

1994

Weed sci.

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Membranes define the outer boundary of the living protoplast and the internal compartmentation of plant cells. From a structural point of view, membranes consist of a lipid bilayer and proteins essential for functions such as solute transport, signal transduction, and numerous metabolic reactions. While membranes can represent a significant barrier to the free movement of many solutes, those with sufficient lipid solubility may move across membranes by dissolving into the lipid bilayer. However, selective membrane transport is generally observed for hydrophilic solutes such as mineral nutrients and cell metabolites. Such selective transport requires an input of metabolic energy, and in plants this occurs via the production of proton electrochemical gradients across the membrane by substrate- (ex. ATP, PPi) driven proton pumps. Selective solute transport is then mediated by membrane-associated secondary transport systems which utilize the proton electrochemical gradient to drive the transport process. This review of membrane structure and transport system function provides a background for a further examination of herbicide interactions with plant membranes.

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Studies on the Reaction Mechanism and Transport Function of P-type ATPases Associated with the Plant Plasma Membrane

Cited by 4 publications

References 45 publications

Calcium transport across plasma membrane vesicles isolated from shoots of Stellaria media and Avena sativa

Calcium transport across plasma membrane vesicles isolated from shoots of Stellaria media and Avena sativa

Characterisation of a Ca²⁺‐dependent ATP hydrolysis associated with the vacuolar membrane of wheat roots

Membranes and Transport Systems in Plants: An Overview

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Studies on the Reaction Mechanism and Transport Function of P-type ATPases Associated with the Plant Plasma Membrane

Cited by 4 publications

References 45 publications

Calcium transport across plasma membrane vesicles isolated from shoots of Stellaria media and Avena sativa

Calcium transport across plasma membrane vesicles isolated from shoots of Stellaria media and Avena sativa

Characterisation of a Ca2+‐dependent ATP hydrolysis associated with the vacuolar membrane of wheat roots

Membranes and Transport Systems in Plants: An Overview

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Product

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Characterisation of a Ca²⁺‐dependent ATP hydrolysis associated with the vacuolar membrane of wheat roots