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XB-ART-35358
J Physiol 2007 May 15;581Pt 1:33-50. doi: 10.1113/jphysiol.2007.128389.
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A conductive pathway generated from fragments of the human red cell anion exchanger AE1.

Parker MD, Young MT, Daly CM, Meech RW, Boron WF, Tanner MJ.


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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.

???displayArticle.pubmedLink??? 17317744
???displayArticle.pmcLink??? PMC2075216
???displayArticle.link??? J Physiol
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Species referenced: Xenopus laevis
Genes referenced: nbl1 pycard slc26a7 slc4a1 uqcc6

References [+] :
Barish, A transient calcium-dependent chloride current in the immature Xenopus oocyte. 1983, Pubmed, Xenbase