Sensitivity and reversibility of Ca-dependent inhibition of the (Na+ + K+)-ATPase of human red blood cells

Douglas R. Yingst, Petra M. Polasek

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The sensitivity of the (Na+ + K+)-ATPase to inhibition by Ca was increased 30-fold by a partially purified extract of human red cell hemolysate. The hemolysate fraction reduced the concentration of free Ca required for 50% inhibition from 30 μM to approx. 1 μM. Ca-dependent inhibition of the (Na+ + K+)-ATPase in the presence and absence of the hemolysate fraction was completely reversible. The hemolysate fraction also stimulated the Ca2+-ATPase and increased its affinity for Ca. In the presence of the hemolysate fraction, the concentration of free Ca that inhibited the (Na+ + K+)-ATPase by 50% was similar to that which half-maximally stimulated the Ca2+-ATPase. Boiling the fraction destroyed its effect on the (Na+ + K+)-ATPase, but did not impair its stimulation of the Ca2+-ATPase.

Original languageEnglish (US)
Pages (from-to)282-286
Number of pages5
JournalBBA - Biomembranes
Issue number2
StatePublished - Mar 14 1985



  • (Na + K)-ATPase
  • Ca inhibition
  • Erythrocyte hemolysate

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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