A conductive pathway generated from fragments of the human red cell anion exchanger AE1

Mark D Parker, Mark T Young, Christopher M Daly, Robert W Meech, Walter F Boron, Michael J A Tanner

Research output: Contribution to journalArticle (Academic Journal)

16 Citations (Scopus)

Abstract

Human red cell anion exchanger AE1 (band 3) is an electroneutral Cl-HCO3- exchanger with 12-14 transmembrane spans (TMs). Previous work using Xenopus oocytes has shown that two co-expressed fragments of AE1 lacking TMs 6 and 7 are capable of forming a stilbene disulphonate-sensitive (36)Cl-influx pathway, reminiscent of intact AE1. In the present study, we create a single construct, AE1Delta(6: 7), representing the intact protein lacking TMs 6 and 7. We expressed this construct in Xenopus oocytes and evaluated it employing a combination of two-electrode voltage clamp and pH-sensitive microelectrodes. We found that, whereas AE1Delta(6: 7) has some electroneutral Cl-base exchange activity, the protein also forms a novel anion-conductive pathway that is blocked by DIDS. The mutation Lys(539)Ala at the covalent DIDS-reaction site of AE1 reduced the DIDS sensitivity, demonstrating that (1) the conductive pathway is intrinsic to AE1Delta(6: 7) and (2) the conductive pathway has some commonality with the electroneutral anion-exchange pathway. The conductance has an anion-permeability sequence: NO3- approximately I- > NO2- > Br- > Cl- > SO4(2-) approximately HCO3- approximately gluconate- approximately aspartate- approximately cyclamate-. It may also have a limited permeability to Na+ and the zwitterion taurine. Although this conductive pathway is not a usual feature of intact mammalian AE1, it shares many properties with the anion-conductive pathways intrinsic to two other Cl-HCO3- exchangers, trout AE1 and mammalian SLC26A7.

Translated title of the contributionA conductive pathway generated from fragments of the human red cell anion exchanger AE1
Original languageEnglish
Pages (from-to)33-50
Number of pages18
JournalJournal of Physiology
Volume581
Issue numberPt 1
DOIs
Publication statusPublished - May 2007

Bibliographical note

Publisher: Blackwell

Keywords

  • 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid
  • Amino Acid Transport Systems, Neutral
  • Animals
  • Anion Exchange Protein 1, Erythrocyte
  • Chloride-Bicarbonate Antiporters
  • Electrophysiology
  • Female
  • Gene Expression Regulation
  • Humans
  • Hydrogen-Ion Concentration
  • Mutation
  • Oocytes
  • Patch-Clamp Techniques
  • Peptide Fragments
  • Signal Transduction
  • Taurine
  • Xenopus laevis

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