کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1959562 | 1057941 | 2005 | 11 صفحه PDF | دانلود رایگان |
Transport kinetics have been examined in erythrocyte anion transporter AE1 that has been chemically modified to convert glutamate 681 to an alcohol (E681OH AE1). Outward conductive Cl− flux in E681OH AE1 is inhibited by removal of extracellular Cl−; this effect is the opposite of that in native AE1 and is consistent with coupled electrogenic 2:1 Cl−/Cl− exchange. A second Cl− binding/transport site is also suggested by the characteristics of S35O42− flux in E681OH AE1: bilateral and cis Cl−, which are normally inhibitory, accelerate S35O42− flux. These effects would be expected if Cl− binds to a second transport site on SO42−-loaded E681OH AE1, thereby allowing Cl−/SO42− cotransport. Alternatively, the data can be explained without proposing Cl−/SO42− cotransport if the rate-limiting event for S35O42−/SO42− exchange is external SO42− release, and the binding of external Cl− accelerates SO42− release. With either interpretation, these data indicate that E681OH AE1 has a binding/transport site for Cl− that is distinct from the main transport site. The effects of graded modification of E681 or inhibition by H2DIDS are consistent with the idea that the new Cl− binding site is on the same E681OH-modified subunit of the AE1 dimer as the normal transport site.
Journal: - Volume 88, Issue 4, April 2005, Pages 2681–2691