Journal ArticleDOI
E2P phosphoforms of Na,K-ATPase. I. Comparison of phosphointermediates formed from ATP and Pi by their reactivity toward hydroxylamine and vanadate.
TLDR
It is suggested that the two phosphoenzyme species formed either from ATP or Pi, especially in their reactivity to N-methyl hydroxylamine, are two subconformations of the E2P phosphoform.Abstract:
The properties of Na,K-ATPase phosphoenzymes formed either from ATP in the presence of Mg2+ and Na+ or from Pi in the absence of alkali cations were investigated by biochemical methods and spectrofluorometry employing the styryl dye RH421. We characterized the phosphoenzyme species by their reaction to N-methyl hydroxylamine, which attacks specifically the protein-phosphate bond. We studied reactions of the phospho- and dephospho-enzymes with vanadate, which is a transition-state analogue of phosphate in this enzyme. On the basis of substantial differences in the properties of the phosphoenzyme species formed either from ATP or Pi, especially in their reactivity to N-methyl hydroxylamine, it is suggested that the two phosphoenzyme species are two subconformations of the E2P phosphoform. Analysis of the RH421 fluorescence responses under a variety of experimental conditions and comparing different enzyme sources suggested that the increase of RH421 fluorescence induced by inorganic phosphate in the absence of alkali cations is associated with the formation of the covalent acyl-phosphate bond.read more
Citations
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Journal ArticleDOI
Crystal structure of the high-affinity Na+,K+-ATPase–ouabain complex with Mg2+ bound in the cation binding site
TL;DR: The crystal structure of the phosphorylated pig kidney Na+,K+-ATPase in complex with the CTS representative ouabain is described, establishing a basis for the interpretation of the biochemical evidence pointing at direct K+–Mg2+ competition and explaining the well-known antagonistic effect of K+ on CTS binding.
Journal ArticleDOI
The ATP Hydrolytic Activity of Purified ZntA, a Pb(II)/Cd(II)/Zn(II)-translocating ATPase from Escherichia coli
TL;DR: The results confirm that ZntA is the first Pb(II)-dependent ATPase discovered to date, and are consistent with the physiological role ofZntA as mediator of resistance to toxic concentrations of the divalent soft metals, Pb (II), Cd(II), and Zn(II) by ATP-dependent efflux.
Journal ArticleDOI
Structural insights into the high affinity binding of cardiotonic steroids to the Na+,K+-ATPase.
Laure Yatime,Mette Laursen,Mette Laursen,J. Preben Morth,J. Preben Morth,Mikael Esmann,Poul Nissen,Poul Nissen,Natalya U. Fedosova,Natalya U. Fedosova +9 more
TL;DR: The observed re-arrangements of the Na+,K+-ATPase stabilized by cardiotonic steroids may affect protein-protein interactions within the intracellular signal transduction networks.
Journal ArticleDOI
Modulation by ammonium ions of gill microsomal (Na+,K+)-ATPase in the swimming crab Callinectes danae: a possible mechanism for regulation of ammonia excretion
D. C. Masui,Rosa dos Prazeres Melo Furriel,John Campbell McNamara,Fernando L. Mantelatto,Francisco A. Leone +4 more
TL;DR: Ammonium and potassium ions synergistically stimulated the enzyme, increasing specific activities up to 90%, suggesting that these ions bind to different sites on the molecule.
Journal ArticleDOI
Modulation of Na,K-ATPase by phospholipids and cholesterol. II. Steady-state and presteady-state kinetics.
TL;DR: The fatty acid and cholesterol composition of the native Na,K-ATPase membrane preparation showed a remarkable similarity to the lipid composition known to support maximum hydrolytic capacity as determined from in vitro experiments.
References
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Journal ArticleDOI
A specific micromethod for the determination of acyl phosphates
TL;DR: In this communication, a method is described which utilizes the reaction of acyl phosphates with hydroxylamine and the acyl part of the acid anhydride is converted into hydroxamic acid.
Journal ArticleDOI
The reversible delipidation of a solubilized sodium-plus-potassium ion-dependent adenosine triphosphatase from the salt gland of the spiny dogfish.
TL;DR: A microsomal fraction rich in Na+, K+-ATPase (sodium-plus-potassium ion-dependent adenosine triphosphatase) and the corresponding K-dependent p-nitrophenyl phosphatase from the rectal salt gland of the spiny dogfish was solubilized by treatment with deoxycholate at high ionic strength.
Journal ArticleDOI
Partial reactions of the Na,K-ATPase: determination of rate constants.
TL;DR: Experiments designed to characterize several partial reactions of the Na,K-ATPase and to demonstrate that a model can be defined that reproduces most of the transport features of the pump with a single set of kientic parameters indicate further that the conformational transition E1P-->P-E2 is the rate limiting process of theNa+ translocation.
Journal ArticleDOI
Synthesis of adenosine triphosphate and exchange between inorganic phosphate and adenosine triphosphate in sodium and potassium ion transport adenosine triphosphatase.
K Taniguchi,RL Post +1 more
TL;DR: It is suggested that binding of sodium ion to a low affinity site on phosphoenzyme formed from inorganic phosphate is sufficient to induce a conformational change in the active center which permits transfer of the phosphate group to adenosine diphosphate.