JBC, Vol. 250, Issue 18, 7257-7265, Sep, 1975
Antigenic differences in (Na+, K+)-ATPase preparations isolated from various organs and species
J. L. McCans, G. E. Lindenmayer, B. J. Pitts, M. V. Ray, B. D. Raynor, V. P. Butler Jr and A. Schwartz
Antisera to purified (Na+, K+)-ATPase raised in rabbits and in sheep were
purified by an absorption procedure employing purified canine kidney (Na+,
K+)-ATPase. The antibodies were fractionated into two components, one which
inhibited catalytic activity, and a second which inhibited ouabain binding.
Under certain conditions, the fraction that inhibited ouabain binding also
inhibited catalytic activity, and the effectiveness of both was dependent
to some extent on the ligands present in the incubation medium. Thus, both
antibody fractions appeared to detect conformations of the enzyme that
depended upon ligand-induced perturbations. When the antibody raised
against catalytic activity was incubated with erythrocyte membrane
fragments, an inhibition of the (Na+, K+)-ATPase occurred, but only minimal
or no effect on potassium influx or on digoxin-induced inhibition of
potassium flux in intact erythrocytes was noted. In a similar experiment,
however, the antibody against ouabain binding significantly inhibited
potassium influx, suggesting specificity in terms of the macromolecular
surfaces of the pump which were exposed to the external medium. We
concluded that there may be organ and species differences among (Na+,
K+)-ATPase preparations. Antibodies prepared in rabbits and sheep were
fractionated by absorption to dog brain enzyme. Both the antibody fraction
which bound to the brain enzyme and that which did not bind inhibited the
dog kidney (Na+, K+)-ATPase, but only the former inhibited dog brain (Na+,
K+)-ATPase. When the two fractions were recombined, inhibition was restored
to the extent of the unfractionated antibody.
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