Cloning and expression of the Na+/H+ exchanger from Amphiuma RBCs: Resemblance to mammalian NHE1

Lee Anne McLean, Shaheen Zia, Fredric A Gorin, Peter M Cala

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

The cDNA encoding the Na+/H+ exchanger (NHE) from Amphiuma erythrocytes was cloned, sequenced, and found to be highly homologous to the human NHE1 isoform (hNHE1), with 79% identity and 89% similarity at the amino acid level. Sequence comparisons with other NHEs indicate that the Amphiuma tridactylum NHE isoform 1 (atNHE1) is likely to be a phylogenetic progenitor of mammalian NHE1. The atNHE1 protein, when stably transfected into the NHE- deficient AP-1 cell line (37), demonstrates robust Na+-dependent proton transport that is sensitive to amiloride but not to the potent NHE1 inhibitor HOE-694. Interestingly, chimeric NHE proteins constructed by exchanging the amino and carboxy termini between atNHE1 and hNHE1 exhibited drug sensitivities similar to atNHE1. Based on kinetic, sequence, and functional similarities between atNHE1 and mammalian NHE1, we propose that the Amphiuma exchanger should prove to be a valuable model for studying the control of pH and volume regulation of mammalian NHE1. However, low sensitivity of atNHE1 to the NHE inhibitor HOE-694 in both native Amphiuma red blood cells (RBCs) and in transfected mammalian cells distinguishes this transporter from its mammalian homologue.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume276
Issue number5 45-5
StatePublished - 1999

Keywords

  • Amiloride
  • HOE-694
  • Intracellular pH
  • Red blood cells
  • Sodium/proton antiport

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology
  • Physiology (medical)

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