(Na+,K+)-ATPase: a new assay of Na+-ATPase reveals covert anti-pump antibodies |
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| Authors: | D B Schenk R Grosse M H Ellisman V Bradshaw H L Leffert |
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| Affiliation: | 1. Department of Medicine, Division of Pharmacology, M-013 H, University of California-San Diego, La Jolla, California 92093 USA;2. Department of Neurosciences, M-008, University of California-San Diego, La Jolla, California 92093 USA;3. Biomembrane Section, Central Institute of Molecular Biology, Academy of Sciences, 1115 Berlin-Buch, East Berlin, German Democratic Republic |
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| Abstract: | A new assay is described for rat (Na+,K+)-ATPase [EC 3.6.1.3] prepared from renal medullary or crude liver membranes. With ATP at 1 μm, initial rates of ouabain-sensitive decreases in substrate concentrations are followed by measuring diminished ATP-driven luciferin-luciferase light production. Under these conditions, using highly purified enzyme preparations, Na+ and K+ ions stimulate and inhibit initial ATP hydrolysis rates, respectively. Therefore, it is likely that the assay measures Na+-ATPase partial reactions of the pump. A monospecific polyclonal rabbit anti-rat pump antiserum blocks Na+-dependent ATPase measured with the luciferase-linked ATPase assay, whereas conventional assays of purified pump activity at 3.0 mm ATP fail to reveal immunochemical blockade. |
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| Keywords: | To whom reprint requests should be addressed. |
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