Na+-dependent purine nucleoside transporter from human kidney:: cloning and functional characterization
Na+-dependent purine nucleoside transporter from human kidney:: cloning and functional characterization
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DOI：
10.1152/ajprenal.1997.273.6.f1058
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发表时间：
1997-12-01
影响因子：
4.2
通讯作者：
Giacomini, KM
中科院分区：
文献类型：
--
作者：
Wang, J;Su, SF;Giacomini, KM
许多嘌呤核苷及其类似物在肾脏中被活跃地转运。利用同源克隆策略和逆转录酶-聚合酶链式反应，我们从人肾中分离到一个编码钠离子依赖的核苷转运蛋白hSPNT1的基因。在非洲爪哇卵母细胞中的功能表达表明，hSPNT1是一种依赖于Na+的核苷转运蛋白，它选择性地转运嘌呤核苷，但也转运尿苷。尿苷与hSPNT1相互作用的米氏常数(K-m)(80mM)显著高于肌苷(4.5mM)。HSPNT1由653个氨基酸组成，与已克隆的大鼠钠核苷转运蛋白SPNT有81%的同源性，但在NH2末端的一级结构上与SPNT有明显的不同。此外，在hSPNT1基因的3‘非翻译区还存在一个Alu重复元件(类似于282bp)。Northern分析表明，hSPNT1的多个转录本广泛分布于包括肾脏在内的人体组织中。相反，大鼠SPNT转录本在肾脏中缺失，并高度定位于肝脏和肠道。HSPNT1基因被定位在15号染色体上。这是首次证实人类肾脏中存在嘌呤核苷转运体。
Many purine nucleosides and their analogs are actively transported in the kidney. Using homology cloning strategies and reverse transcriptase-polymerase chain reactions, we isolated a cDNA encoding a Na+-dependent nucleoside transporter, hSPNT1, from human kidney. Functional expression in Xenopus laevis oocytes identified hSPNT1 as a Na+-dependent nucleoside transporter that selectively transports purine nucleosides but also transports uridine. The Michaelis constant (K-m) of uridine (80 mu M) in interacting with hSPNT1 was substantially higher than that of inosine (4.5 mu M). hSPNT1 (653 amino acids) is 81% identical to the previously cloned rat Na+-nucleoside transporter, SPNT, but differs markedly from SPNT in terms of its primary structure in the NH2 terminus. In addition, an Alu repetitive element (similar to 282 bp) is present in the 3'-untranslated region of the hSPNT1 cDNA. Northern analysis revealed that multiple transcripts of hSPNT1 are widely distributed in human tissues including human kidney. In contrast, rat SPNT transcripts are absent in kidney and highly localized to liver and intestine. The hSPNT1 gene was localized to chromosome 15. This is the first demonstration of a purine nucleoside transporter in human kidney.