Species-specific transport systems for nucleobases and urate in small intestine.

碱基是构成核苷和核酸的重要化合物。虽然长期以来一直认为特定的转运体参与了它们的肠道吸收，但它们的分子实体在哺乳动物中还没有被确定。在存在性研究中，我们成功地鉴定了大鼠SLc23a4是第一个钠依赖的核苷酸转运蛋白(SNBT1)，它只在大鼠的小肠中高效表达。当在HEK293细胞中瞬时表达时，大鼠SNBT1可以转运尿嘧啶、胸腺嘧啶、鸟嘌呤、次黄嘌呤和黄嘌呤等碱基，也可以转运尿酸。还发现与rSNBT1基因同源的基因在人类中存在遗传缺陷。这可能在核苷酸和尿酸盐的运输和代谢中具有生物学和进化意义。

Nucleobases are important compounds that constitute nucleosides and nucleic acids. Although it has long been suggested that specific transporters are involved in their intestinal absorption, their molecular entities have not been identified in mammals. In the presence study, we could successfully identify rat Slc23a4 as the first sodium dependent nucleobase transporter(SNBT1), which is highly and only expressed in rat small intestine. When transiently expressed in HEK293 cells, rat SNBT1 could transport nucleobases such as uracil, thymine, guanine, hypoxanthine and xanthine, as well as urate. It was also found that the gene orthologous to the rSNBT1 gene is genetically defective in humans. This may have a biological and evolutional meaning in the transport and metabolism of nucleobases and urate.