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

Parker, Mark D., Young, Mark Thomas ORCID: https://orcid.org/0000-0002-9615-9002, 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:	Schools > Biosciences
Subjects:	Q Science > Q Science (General) Q Science > QH Natural history > QH301 Biology
Publisher:	The Physiological Society
ISSN:	0022-3751
Last Modified:	25 Oct 2022 09:15
URI:	https://orca.cardiff.ac.uk/id/eprint/57836

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