Daniel H, Herget M
Biochemistry of Nutrition Unit, University of Giessen, Germany.
Am J Physiol. 1997 Jul;273(1 Pt 2):F1-8. doi: 10.1152/ajprenal.1997.273.1.F1.
Renal epithelial cells express membrane transport proteins capable of cellular uptake of a large variety of di- and tripeptides. These transporters contribute to renal amino acid homeostasis and the efficiency of conservation of amino acid nitrogen. In addition, these transporters appear to play a role in the renal handling of xenobiotics that possess a peptide backbone. Peptide carriers specialized in transport of di- and tripeptides have been identified in bacteria, fungi, plants, and epithelial cells of mammalian intestine and kidney. They appear to represent an archaic transporter family conserved throughout evolution. As a unique feature, these peptide carriers utilize a transmembrane-electrochemical proton gradient as the driving force that enables them to transport peptides against a concentration gradient. Renal peptide transporters have been characterized in terms of mechanism of transport function and substrate specificity in a number of model systems. Within the last two years, kidney peptide transporters of a variety of species have been identified by cloning techniques. In this review we discuss the physiological importance of renal peptide carriers and the transport mechanisms at the cellular level. We also present the recent advancements in functional expression of the cloned proteins that provide first insights into their molecular architecture and mode of operation.
肾上皮细胞表达能够摄取多种二肽和三肽的膜转运蛋白。这些转运蛋白有助于维持肾脏氨基酸稳态以及氨基酸氮的保存效率。此外，这些转运蛋白似乎在具有肽骨架的外源性物质的肾脏处理过程中发挥作用。专门负责转运二肽和三肽的肽载体已在细菌、真菌、植物以及哺乳动物肠道和肾脏的上皮细胞中被鉴定出来。它们似乎代表了一个在整个进化过程中都保守的古老转运蛋白家族。作为一个独特的特征，这些肽载体利用跨膜电化学质子梯度作为驱动力，使其能够逆浓度梯度转运肽。在许多模型系统中，已根据转运功能机制和底物特异性对肾肽转运蛋白进行了表征。在过去两年中，通过克隆技术已鉴定出多种物种的肾脏肽转运蛋白。在本综述中，我们讨论了肾肽载体在生理上的重要性以及细胞水平的转运机制。我们还介绍了克隆蛋白功能表达方面的最新进展，这些进展为其分子结构和运作模式提供了初步见解。
