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

Parker, Mark D., Young, Mark Thomas, Daly, Christopher M., Meech, Robert W., Boron, Walter F. and Tanner, Michael J. A. 2007. A conductive pathway generated from fragments of the human red cell anion exchanger AE1. The Journal of Physiology 581 (1) , pp. 33-50. 10.1113/jphysiol.2007.128389

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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.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Biosciences
Subjects: Q Science > Q Science (General)
Q Science > QH Natural history > QH301 Biology
Publisher: The Physiological Society
ISSN: 0022-3751
Last Modified: 02 May 2019 12:12
URI: http://orca.cf.ac.uk/id/eprint/57836

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