Isozymes of the Na+/K+-ATPase.

The proton-translocating ATPase of the fungal plasma membrane☆

Structure and function of proton translocating ATPase in plasma membranes of plants and fungi.

The plant plasma membrane H(+)-ATPase: structure, function and regulation.

The function of Gp170, the multidrug resistance gene product, in rat liver canalicular membrane vesicles.

The purified plasma membrane ATPase of the yeast Schizosaccharomyces pombe forms a phosphorylated intermediate.

Exchange of Oxygen Between Phosphate and Water Catalyzed By the Plasma-membrane Atpase From the Yeast Schizosaccharomyces-pombe

A maize-root microsomal fraction was enriched in ATPase by treatment with Triton X-100. This activity, which reached 1.2–2.0/μmol Pi× min−1× gm protein−1, was specific for ATP, very slightly stimulated by K+, inhibited by orthovanadate and diethylstibestrol, resistant to oligomycin and azide, and had a Km of 1.2 mM MgATP.

Incubation of th emicrosomal fraction with [y32-P]ATP followed by electrophoresis in acid conditions revealed the presence of several phosphoproteins. The phosphorylation of a 110000-M4 polypeptide reached the steady-state level in less than 5 s and rapidly turned over the phosphate group. The phosphorylation level was an hyperbolic function of the [ATP] with a Km of 0.6 mM, suggesting that the rat e of Pi production was proportional to the phosphoprotein concentration. The extent of phosphoprotein was decreased by vanadate and diethylstilbestrol. The phosphorylation level was 30% decreased by 50 mM K+ or Na+ while the ATPase activity was slightly stimulated (12% and 5%. respectively). The polypeptide could not bephosphorylated in reverse by Pi. This phosphorylated intermediate from maize-root microsomes exhibits molecular properties characteristic of transport ATPases such as the yeast plasma membrance H+ -translocating ATPase. This similarity indicates existence of a transport ATPase in plant plasma membranes.

Three other plant microsomal polypeptides (Mr= 52000, 17000 and 16000) and a low molecular weight component (Mr < 1000) were phosphorylated much more slowly, were not undergoing a rapid turnover and were not hydrolysed by hydroxylamine. These phosphoproteins and the Mr < 1000 phosphorylated component were inhibited by vanadate and diethylstilbestrol. These properties are similar to those of the protein kinase activity recently described in yeast plasma membranes.

Phosphorylated Intermediate of a Transport ATPase and Activity of Protein Kinase in Membranes from Corn Roots

A new procedure for large-scale preparation of plasma-membrane-bound ATPase from Saccharomyces cerevisiae is described. The crude membrane fraction is purified by selective extraction with three successive detergents: deoxycholate (0.25 mg/mg protein), Triton X-100 (0.25%) and lysophosphatidylcholine (1 mg/mg protein). These treatments extract the mitochondria and strip the plasma membrane. From 1 kg commercial baker's yeast, 200 mg of plasma membrane proteins are isolated in 2--3 days. Plasma-membrane-bound ATPase of specific activity of 10--13 mumol Pi x min-1 x mg protein-1 is obtained with a yield estimated to 60%. Dodecylsulfate/polyacrylamide gel electrophoresis shows three predominant polypeptides of Mr = 95000, 70000 and 56000 in the purified membrane fraction. The major polypeptide of Mr = 95000 identified as the ATPase subunit is phosphorylated by millimolar concentrations of ATP. The phosphorylated intermediate reaches the steady-state level in less than 100 ms and turns over very rapidly. It is hydrolyzed by hydroxylamine. Its formation is prevented by the ATPase inhibitors vanadate and Dio-9, a plasma-membrane ATPase inhibitor of unknown structure. At least four other membrane proteins are phosphorylated with much slower kinetics, presumably through the action of protein-kinase(s).

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1432-1033.1981.tb05621.x

Large-scale purification and phosphorylation of a detergent-treated adenosine triphosphatase complex from plasma membrane of Saccharomyces cerevisiae.

Publisher Summary This chapter reviews the contributions made to the mechanism of the H + -adenosine triphosphatase (ATPase) from yeast plasma membrane by using chemical approaches that give direct access to phosphorylated species located in the catalytic site of the enzyme. The chapter presents the studies on two catalytic intermediates of adenosine triphosphate (ATP) hydrolysis: E–P and E·P i . The chapter presents an efficient radiochemical technique, which shows that E–P is an aspartyl β -phosphate. The E·Ρ 1 species has been traced by exchange of 18 O oxygens between phosphate and water. The rotational freedom of the phosphate in the catalytic site allows the different oxygens of a given P i molecule to be successively involved in hydration/dehydration cycles with the same carboxyl group. The chapter also discusses the impact of 18 O technology for the identification of partial reactions of the hydrolytic pathway.

A. Amory

Papers

The purified plasma membrane ATPase of the yeast Schizosaccharomyces pombe forms a phosphorylated intermediate.

Exchange of Oxygen Between Phosphate and Water Catalyzed By the Plasma-membrane Atpase From the Yeast Schizosaccharomyces-pombe

Phosphorylated Intermediate of a Transport ATPase and Activity of Protein Kinase in Membranes from Corn Roots

Large-scale purification and phosphorylation of a detergent-treated adenosine triphosphatase complex from plasma membrane of Saccharomyces cerevisiae.

Contribution of 18O Technology to the Mechanism of the H+-ATPase from Yeast Plasma Membrane