Molecular physiology of the Rh ammonia transport proteins.
Molecular physiology of the Rh ammonia transport proteins.
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DOI：
10.1097/mnh.0b013e32833bfa4e
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发表时间：
2010-09
影响因子：
3.2
通讯作者：
Verlander JW
中科院分区：
文献类型：
--
作者：
Weiner ID;Verlander JW
最近的研究已经确定了一个新的家庭的氨特异性转运蛋白，Rh糖蛋白，使NH3特异性运输。本文综述了Rh糖蛋白在肾氨转运中的作用。Rh糖蛋白RhAG/Rhag、RhBG/Rhbg和RhCG/Rhcg以分子NH3的形式转运氨，尽管有一些证据表明NH 4+转运的可能性。RhAG/Rhag仅在红细胞中表达，而不在肾脏中表达。Rhbg和Rhcg在远端肾单位部位表达，从远曲小管通过内髓集合管，具有基底外侧Rhbg表达以及顶端和基底外侧Rhcg表达。Rhbg是否有助于肾氨转运仍有争议。在多个实验模型和遗传缺失研究中，Rhcg表达与氨排泄平行，无论是全球性的还是集合管特异性的，都证明了Rhcg在基础和酸中毒刺激的肾氨排泄中的关键作用。X射线晶体学已经定义了Rh糖蛋白介导的氨转运中的关键结构元素。最后，Rh糖蛋白也可以作为CO2转运蛋白。NH3的迁移不再仅仅是通过NH3的扩散运动进行的。转运蛋白介导的NH3运动是氨代谢的基础。
Recent studies have identified a new family of ammonia-specific transporters, Rh glycoproteins, which enable NH3-specific transport. The purpose of this review is to summarize recent evidence regarding the role of Rh glycoproteins in renal ammonia transport. The Rh glycoproteins, RhAG/Rhag, RhBG/Rhbg and RhCG/Rhcg, transport ammonia in the form of molecular NH3, although there is some evidence suggesting the possibility of NH4+ transport. RhAG/Rhag is expressed only in erythrocytes, and not in the kidney. Rhbg and Rhcg are expressed in distal nephron sites, from the distal convoluted tubule through the inner medullary collecting duct, with basolateral Rhbg expression and both apical and basolateral Rhcg expression. Whether Rhbg contributes to renal ammonia transport remains controversial. Rhcg expression parallels ammonia excretion in multiple experimental models and genetic deletion studies, both global and collecting duct-specific, demonstrate a critical role for Rhcg in both basal and acidosis-stimulated renal ammonia excretion. X-ray crystallography has defined critical structural elements in Rh glycoprotein-mediated ammonia transport. Finally, Rh glycoproteins may also function as CO2 transporters. No longer can NH3 transport be considered to occur only through diffusive NH3 movement. Transporter-mediated NH3 movement is fundamental to ammonia metabolism.