N-ethymaleimide-sensitive ATPase activity was measured in crude homogenates of gill tissue from rainbow trout using a coupled-enzyme ATPase assay in the presence of EGTA, ouabain and azide. This NEM-sensitive ATPase activity, determined to be about 1.5 mmolmg21 protein h21 at 15 ̊C for freshwater trout, is also inhibited by other H+ATPase blockers such as DCCD, DES, PCMBS and bafilomycin. It is ...

The Ca(2+)-ATPase of skeletal-muscle sarcoplasmic reticulum, solubilized in monomeric from in C12E8, has been reconstituted by dialysis into sealed vesicles of dioleoyl phosphatidylcholine [di(C18:1)PC], dimyristoleoyl phosphatidylcholine [di(C14:1)PC], dinervonyl phosphatidylcholine [di(C24:1)PC] or dipalmitoyl phosphatidylcholine [di(C16:0)PC] in the gel phase, at a phospholipid/ATPase molar ...

Apart from Na(+),K(+)-ATPase, a second sodium pump, Na(+)-stimulated, K(+)-independent ATPase (Na(+)-ATPase) is expressed in proximal convoluted tubule of the mammalian kidney. The aim of this study was to develop a method of Na(+)-ATPase assay based on the method previously used by us to measure Na(+),K(+)-ATPase activity. The ATPase activity was assayed as the amount of inorganic phosphate li...

To identify the functional unit of Ca(2+)-ATPase in the sarcoplasmic reticulum, we assessed Ca(2+)-transport activities occurring on sarcoplasmic reticulum membranes with different combinations of active and inactive Ca(2+)-ATPase molecules. We prepared heterodimers, consisting of a native Ca(2+)-ATPase molecule and a Ca(2+)-ATPase molecule inactivated by FITC labelling, by fusing vesicles load...

The plasma membrane H (+) -ATPase provides the driving force for solute transport via an electrochemical gradient of H (+) across the plasma membrane, and regulates pH homeostasis and membrane potential in plant cells. However, the plasma membrane H (+) -ATPase in non-vascular plant bryophyte is largely unknown. Here, we show that the moss Physcomitrella patens, which is known as a model bryop...

The plasma membrane H-ATPase generates an electrochemical gradient of H across the plasma membrane that provides the driving force for solute transport and regulates pH homeostasis and membrane potential in plant cells. Recent studies have demonstrated that phosphorylation of the penultimate threonine in H-ATPase and subsequent binding of a 14-3-3 protein is the major common activation mechanis...

We previously have demonstrated that the colonic P-ATPase alpha subunit cDNA encodes an H,K-ATPase when expressed in Xenopus laevis oocytes. Besides its high level of amino acid homology (75%) with the Na,K-ATPase, the colonic H,K-ATPase also shares a common pharmacological profile with Na,K-ATPase, because both are ouabain-sensitive and Sch 28080-insensitive. These features raise the possibili...

The ATPase 6 accessory protein 2 (ATP6AP2)/(pro)renin receptor (PRR) is essential for the biogenesis of active vacuolar H(+)-ATPase (V-ATPase). Genetic deletion of ATP6AP2/PRR causes V-ATPase dysfunction and compromises vesicular acidification. Here, we characterized the domains of ATP6AP2/PRR involved in active V-ATPase biogenesis. Three forms of ATP6AP2/PRR were found intracellularly: full-le...

PURPOSE Earlier studies from this laboratory demonstrated the ability of lens epithelium to synthesize new Na,K-adenosine triphosphatase (Na,K-ATPase) catalytic subunit (alpha) polypeptide under conditions of increased ion permeability. In the present study, the authors considered whether continuous synthesis of Na,K-ATPase protein is necessary for maintenance of Na,K-ATPase activity in lens ce...

Secretory activity in blowfly salivary glands is activated by the hormone serotonin. We have investigated the distribution and activity of two cation pumps that are possibly involved with transepithelial ion transport, i.e. Na(+)/K(+)-ATPase and vacuolar-type H(+)-ATPase (V-ATPase). By immunofluorescence labelling of secretory cells, Na(+)/K(+)-ATPase was localized on the basolateral plasma mem...