协同运输机
化学
细胞生物学
分子生物学
钠氢反转运蛋白
基因亚型
肾单位
肾
顶膜
上皮极性
插层细胞
共转运蛋白
生物物理学
基因表达
重吸收
作者
Michael F. Romero,Matthias A. Hediger,Emile L. Boulpaep,Walter F. Boron
出处
期刊:Nature
[Springer Nature]
日期:1997-05-22
卷期号:387 (6631): 409-413
被引量:397
摘要
Bicarbonate transporters are the principal regulators of pH in animal cells, and play a vital role in acid–base movement in the stomach, pancreas, intestine, kidney, reproductive system and central nervous system. The functional family of HCO3− transporters includes Cl−–HCO3− exchangers, three Na+/HCO3− cotransporters1–3, a K+/HCO3− cotransporter4,5, and a Na+-driven Cl− –HCO3− exchanger6,7. Molecular information is sparse on HCO3− transporters, apart from Cl− –HCO3− exchangers ('anion exchangers'), whose complementary DNAs were cloned several years ago8–11. Attempts to clone other HCO3− transporters, based on binding of inhibitors, protein purification or homology with anion exchangers, have so far been unsuccessful. Here we monitor the intracellular pH and membrane voltage in Xenopus oocytes to follow the expression of the most electrogenic transporter known: the renal 1:3 electrogenic Na+/HCO3−cotransporter from the salamander Ambystoma tigrinum. We now report the successful cloning and characterization of a cDNA encoding a cation-coupled HCO3− transporter. The encoded protein is 1,035 amino acids long with several potential membrane-spanning domains. We show that when it is expressed in Xenopus oocytes, this protein is electrogenic, Na+ and HCO3− dependent, and blocked by the anion-transport inhibitor DIDS, and conclude that it is the renal electrogenic sodium bicarbonate cotransporter (NBC).
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