Characteristics of antibody inhibition of rat kidney (Na+−K+)-ATPase
- 1 December 1978
- journal article
- research article
- Published by Springer Nature in The Journal of Membrane Biology
- Vol. 44 (1), 85-102
- https://doi.org/10.1007/bf01940575
Abstract
Antibodies which were raised against highly purified membrane-bound (Na+−K+)-ATPase from the outer medulla of rat kidneys inhibit the (Na+−K+)-ATPase activity up to 95%. The antibody inhibition is reversible. The time course of enzyme inhibition and reactivation is biphasic in semilogarithmic plots. In the purified membrane-bound (Na+−K+)-ATPase negative cooperativity was observed (a) for the ATP dependence of the (Na+−K+)-ATPase activity (n=0.86), (b) for the ATP binding to the enzyme (n=0.58), and (c) for the ouabain inhibition of the (Na+−K+)-ATPase activity (n=0.77). By measuring the Na+ dependence of the (Na+−K+-ATPase reaction, a positive homotropic cooperativity (n=1.67) was found. As reactivation of the antibody-inhibited enzyme proceeds very slowly (t 0.5=5.2hr), it was possible to measure characteristics of the antibody-(Na+−K+)-ATPase complex: The antibodies exerted similar effects on the ATP dependence of the (Na+−K+)-ATPase reaction and on the ATP binding of the enzyme.V max of the (Na+−K+)-ATPase reaction and the number of ATP binding sites were reduced whileK 0.5 ATP for the (Na+−K+)-ATPase activity and for the ATP binding were increased by the antibodies. The Hill coefficients for the ATP binding and for the ATP dependence of the enzyme activity were not significantly altered by the antibodies. The antibodies increased theK 0.5 value for the Na+ stimulation of the (Na+−K+)-ATPase activity, but they did not alter the homotropic interactions between the Na+-binding sites. The negative cooperativity which was observed for the ouabain inhibition of the (Na+−K+)-ATPase activity was abolished by the antibodies. The data are tentatively explained by the following model: The antibodies bind to the (Na+−K+)-ATPase from the inner membrane side, reduce the ATP binding symmetrically at the ATP binding sites and reduce thereby also the (Na+−K+)-ATPase activity of the enzyme. The antibodies may inhibit the ATP binding by a direct interaction or by means of a conformational change at the ATP binding sites. This may possibly also lead to the alteration of the Na+ dependence of the (Na+−K+)-ATPase activity and to the observed alteration of the dose response to the ouabain inhibition.Keywords
This publication has 25 references indexed in Scilit:
- 23. Konferenz der Gesellschaft für Biologische Chemie. Biochemical Aspects of Kidney FunctionHoppe-Seyler´s Zeitschrift Für Physiologische Chemie, 1977
- (Na+, K+)-Activated Adenosinetriphosphatase of Axonal Membranes, Cooperativity and Control. Steady-State AnalysisEuropean Journal of Biochemistry, 1976
- Non-uniform populations of g-strophanthin binding sites of (Na+ + K+)-activated ATPase Apparent conversion to uniformity by K+Biochimica et Biophysica Acta (BBA) - Biomembranes, 1976
- Inhibition of the purified sodium-potassium activated adenosinetriphosphatase from the rectal gland of Squalus acanthias by antibody against the glycoprotein subunitBiochemical and Biophysical Research Communications, 1975
- Purification and characterization ofBiochimica et Biophysica Acta (BBA) - Biomembranes, 1974
- Antibodies to pig kidney (Na++K+)-ATPase inhibit the Na+ pump in human red cells provided they have access to the inner surface of the cell membraneBiochimica et Biophysica Acta (BBA) - Biomembranes, 1973
- Na+,K+-ATPase complex: Effects of anticomplex antibody on the partial reactions catalyzed by the complexBiochemical and Biophysical Research Communications, 1972
- On the Mechanism of Na+‐and K+‐Stimulated Hydrolysis of Adenosine TriphosphateEuropean Journal of Biochemistry, 1967
- ANTIBODY AS INHIBITOR OF RIBONUCLEASE: THE ROLE OF STERIC HINDRANCE, AGGREGATE FORMATION, AND SPECIFICITYAnnals of the New York Academy of Sciences, 1963
- Determination of ATP and Related Compounds: Firefly Luminescence and other MethodsPublished by Wiley ,1954