Inducible expression of erythrocyte band 3 protein.
A permanent cell line with inducible expression of the human anion exchanger protein 1 (hAE1) was constructed in a derivative of human embryonic kidney cells (HEK-293). In the absence of the inducer, muristerone A, the new cell line had no detectable hAE1 protein by Western analysis or additional 36Cl flux. Increasing dose and incubation time with muristerone A increased the amount of protein (both unglycosylated and glycosylated). The 4,4'-dinitrostilbene-2, 2'-disulfonate (DNDS)-inhibitable rapid Cl exchange flux was increased up to 40-fold in induced cells compared with noninduced cells. There was no DNDS-inhibitable rapid flux component in noninduced cells. This result demonstrates inducible expression of a new rapid Cl transport pathway that is DNDS sensitive. The additional transport of 36Cl and 35SO4 had the characteristics of hAE1-mediated transport in erythrocytes: 1) inhibition by 250 microM DNDS, 2) activation of 36Cl efflux by external Cl with a concentration producing half-maximal effect of 4.8 mM, 3) activation of 36Cl efflux by external anions that was selective in the order NO3 = Cl > Br > I, and 4) activation of 35SO4 influx by external protons. Under the assumption that the turnover numbers of hAE1 were the same as in erythrocytes, there was good agreement (+/-3-fold) between the number of copies of glycosylated hAE1 and the induced tracer fluxes. This is the first expression of hAE1 in a mammalian system to track the kinetic characteristics of the native protein.
Timmer
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RT
Department of Physiology, Emory University School of Medicine, Atlanta, Georgia 30322-3110, USA.
Gunn
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RB
D001457:Anion Exchange Protein 1, Erythrocyte / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D015153:Blotting, Western; D002460:Cell Line; D002712:Chlorides / Q000378:metabolism; D004441:Ecdysterone / Q000031:analogs & derivatives / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D006801:Humans; D013267:Stilbenes / Q000494:pharmacology
D001457:Anion Exchange Protein 1, Erythrocyte; D002712:Chlorides; D013267:Stilbenes; C055348:muristerone A; D004441:Ecdysterone; C022306:4,4'-dinitro-2,2'-stilbenedisulfonic acid