HETEROGENEITY OF RENAL PEPTIDE TRANSPORTERS

专门的转运蛋白，如肾肽转运系统， 在肽结合的选择性重吸收中起重要作用 氨基酸以及调节血浆浓度， 小肽这一独特的交通系统也具有重要意义。 药理学相关性，因为它识别β 3-内酰胺抗生素 （氨基头孢菌素和氨基青霉素），抗癌化合物 （bestatin）、血管紧张素转化酶抑制剂（喹那普利），以及 结果，是其药代动力学特征的重要决定因素， 毒性和治疗效果。然而，系统的研究表明， 肾肽转运细胞基础相对较少， 几乎没有关于特异性肽的异质性的信息 沿着肾单位。该提案的重点是 哺乳动物肾脏中寡肽转运蛋白的表征， 特别是PEPT 1和PEPT 2的研究，这两种亚型在一种新的， 质子偶联肽转运蛋白家族不断壮大。我们的具体目标 为： 目标1。为了定义在细胞中肽转运活性的异质性， 哺乳动物肾脏不同区域的刷状缘膜 囊泡和杂交体耗竭研究。 目标2.以确定组织分布和肾小管定位 哺乳动物肾脏中的PEPTI和PEPT 2。 目标3：来表征肽和肽的底物特异性， 哺乳动物肾脏特异性寡肽转运蛋白的类似药物 (i.e., PEPT 1和PEPT 2）在非洲爪蟾卵母细胞中表达。 潜在的假设是，对肽转运蛋白的理解 异质性（即，活动，分布-定位，结构- 功能）将提供独特的见解，肾的一般原则， 肽质子共转运在功能以及分子水平。 从拟议的实验中收集的知识也将具有 对应用程序的重大影响，也许设计， 用于治疗感染、癌症、高血压 充血性心力衰竭和潜在的其他疾病状态。 最终，这些研究将为未来的建议铺平道路 关于肾脏中肽转运蛋白的调节 生理和病理条件。

Specialized transporters, such as the renal peptide transport system, play a significant role in the selective reabsorption of peptide-bound amino acids as well as in the regulation of plasma concentrations for small peptides. This unique transport system also has significant pharmacological relevance in that it recognizes Beta3-lactam antibiotics (aminocephalosporins and aminopenicillins), anticancer compounds (bestatin), angiotensin-converting enzyme inhibitors (quinapril) and, as a result, is an important determinant of their pharmacokinetic profile, toxicity and therapeutic efficacy. However, systematic studies concerning the cellular basis of renal peptide transport are relatively few and there is almost no information on the heterogeneity of specific peptide transporters along the nephron. This proposal focuses on the characterization of oligopeptide transporters in mammalian kidney and, in particular, the study of PEPT1 and PEPT2, two isoforms in a novel and growing family of proton-coupled peptide transporters. Our specific aims are: Aim 1. to define the heterogeneity of peptide transport activity in different regions of mammalian kidney using brush border membrane vesicles and hybrid depletion studies. Aim 2. to determine the tissue distribution and tubular localization of PEPTI and PEPT2 in mammalian kidney. Aim 3. to characterize the substrate specificity of peptides and peptide- like drugs for specific oligopeptide transporters in mammalian kidney (i.e., PEPT1 and PEPT2) expressed in Xenopus laevis oocytes. The underlying hypothesis is that an understanding of peptide transporter heterogeneity (i.e., activity, distribution-localization, structure- function) will offer unique insights into the general principles of renal peptide-proton cotransport at a functional as well as molecular level. The knowledge gleaned from the proposed experiments will also have significant implications for the application, and perhaps design, of clinically important drugs used to treat infection, cancer, hypertension, congestive heart failure and potentially other disease states. Ultimately, these studies will pave the way for future proposals concerning the regulation of peptide transporters in kidney under physiological and pathological conditions.