Transmembrane Ca2+ gradient is essential for high anion transport activity of human erythrocytes

Y. P. Tu, C. Feng, H. Xu, Z. Y. Guang, Q. W. Lu, F. Y. Yang

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Abstract

The role of a transmembrane Ca2+ gradient in anion transport by Band 3 of human resealed erythrocyte ghosts has been studied. The results show that a transmembrane Ca2+ gradient is essential for the conformation of erythrocyte Band 3 with higher anion transport activity. The dissipation of the transmembrane Ca2+ gradient by the ionophore A23187 inhibits the anion transport activity. The extent of this inhibition approaches 90% as the Ca2+ concentration on both sides of the ghost membrane is increased to 1.0mM and half-maximum inhibition is observed at 0.25mM Ca2+ Addition of ATP (0.4mM) to the resealing medium can partly reestablish the transmembrane Ca2+ gradient by activation of Ca2+-ATPase and alleviate the inhibition to some extent. N-ethylmaleimide, an inhibitor of erythrocyte Ca2+-ATPase, prevents such restoration. Electron micrographs reveal that numerous larger intramembranous particles can be observed on the P-faces of freeze-fractured resealed ghosts in the absence of a transmembrane Ca2+ gradient.

Original languageEnglish (US)
Pages (from-to)299-311
Number of pages13
JournalBioscience Reports
Volume16
Issue number4
DOIs
StatePublished - Nov 8 1996
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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