Molecular cloning and functional expression of kidney-specific organic anionic drug transporters

肾脏特异性有机阴离子药物转运蛋白的分子克隆及功能表达

基本信息

批准号：
09470025
负责人：
ENDOU Hitoshi
金额：
$ 7.17万
依托单位：
Kyorin University School of Medicine
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

Most drugs ingested into the body are metabolized by drug-metabolizing enzymes in the liver, and converted to more polarized hydrophilic compounds. Thus formed drug metabolites contain either negative or positive charge, and more anionic compounds are produced. To eliminate these drug metabolites out of the body, specific membrane proteins named transporters are required.There are two major pathways for drug elimination, one of which is hepatic one through bile and another is renal one to urine. In this investigation, we tried to clone kidney-specific organic anion transporters, and to characterize several isoforms.In 1997, we could succeed to isolate a novel organic anion transporter from rat kidneys and named it OAT (organic anion transporter) 1. Thereafter, three members of OAT family have been identified. OAT2 is liver-specific having different spectrum of transport substrates from OAT1. OAT3 having 536 amino acid residue is expressed in the liver, kidney and brain showing 49% and 39% identities with OAT1 and OAT2, respectively. OAT3 mediates high affinity transport of PAH, ochratoxin A, and estron sulfate. Human OAT4 is expressed in the kidney and placenta and consists of 550 amino acids having identity at 38%〜44% with OAT1〜3. The OAT4 is also multispecific in substrate recognition, like estron sulfate, dehydroepiandrosterone sulfate, and ochratoxin A.Although we could chine 4 isoforms of OAT family, OAT1〜4, molecular mechanisms on substrate recognition remain to be carried out by further investigation. Since OATs reveal weak but significant similarity in their structure with organic cation transporters and carnitine transporters, possible molecular evolution should be clarified among these families. The multi specificity seen in OATs may be originated from relatively simple substrate binding to the transporters and the hypothesis of two important biding sites like hydrophobic moiety and ionic charge needs to be elucidated.

大多数摄入体内的药物是通过肝脏中的药物代谢酶代谢的，并转化为更偏振的亲水性化合物。形成的药物代谢产物含有负或阳性电荷，并产生更多的阴离子化合物。为了从体内消除这些药物代谢物，需要特定的膜蛋白，称为转运蛋白。消除药物的主要途径有两种，其中之一是肝脏至胆汁，另一种是肾脏尿液。在这项投资中，我们试图克隆肾脏特异性的有机阴离子转运蛋白，并表征了几种同工型。在1997年，我们可以成功地将一种新型有机阴离子转运蛋白与大鼠肾脏分离，并将其命名为OAT（有机阴离子转运蛋白）1。此后，已经确定了三个燕麦家族成员。 OAT2是实时特异性的，具有与OAT1的运输底物不同光谱。 OAT3分别在肝脏，肾脏和大脑中表达了536个氨基酸的保留率，分别显示出49％和39％的OAT1和OAT2身份。 OAT3介导了PAH，Ochratoxin A和Estron硫酸盐的高亲和力转运。人OAT4在肾脏和plapeta中表达，由550个氨基酸组成，具有38％至44％的氨基酸与OAT1至3。OAT4在底物识别中也是多特异性的，尽管我们可以像OAT家族，OAT1-4，OAT1-4的分子识别率一起car ottrate contriews contrientation contrate识别。由于燕麦与有机阳离子转运蛋白和肉碱转运蛋白的结构显示出弱但显着的相似性，因此应在这些家族中阐明可能的分子进化。在燕麦中看到的多种特异性可能起源于相对简单的底物与转运蛋白的结合，并且需要阐明两个重要的贝丁屈服位点，例如疏水部分和离子电荷。