REGULATION OF THE SODIUM/MYO-INOSITOL COTRANSPORTER

肌醇是一种存在于所有细胞中的丰富的糖类。它有两个非常 重要功能：1)是磷脂酰肌醇的前体， 所有细胞质膜的重要组成部分，2)它是一种 相容渗透剂，即与钠和钾相反，其 在不干扰细胞的情况下，细胞内浓度可以增加10倍 功能。虽然肌醇在血浆中的浓度为0.05 mM， 其在大多数细胞中的浓度为LO-2OmM。它以这样的方式进入细胞 钠/肌醇共转运体上的陡峭浓度梯度 由钠的电化学梯度驱动。虽然在细胞内 肌醇缺乏与神经病变和 糖尿病肾病，几乎对糖尿病肾病一无所知 共转运体或其监管。 本项目旨在了解该系统的功能和 钠/肌醇共转运蛋白的克隆与调控 从培养的肾细胞中测序其cDNAs，类似于肾脏 延髓，将他们的肌醇水平提高到&gt；80 mM以回应 高张力。在那个时候，辅酶转运蛋白的活性增加， 共转运蛋白基因表达增加的一些证据。该基因将被命名为 测序以揭示共转运体的一级结构和 促进针对它的抗体的产生。抗体将会是 用来量化肾细胞中共转运体的数量，以便 确定细胞是否积累了更多的肌醇，因为有 更多的共转运体，如果有更多，这是不是因为 增加辅转运体的合成和/或减少其降解。这个 CDNA将被用来构建一个RNA探针来测量细胞的mRNA水平 协同转运体以确定是否确实存在增加的 共转运蛋白mRNA的合成和/或降解是否 受监管的。如果信使核糖核酸合成增加，共转运蛋白的基因 将被克隆以使调节高张力的机制和 其他因素也可以研究。该基因将被用来开发探针，以 克隆钠/肌醇共转运蛋白基因 肾和小肠的顶端质膜，在那里它起作用 将肌醇从管腔输送到血液。序列数据应该产生 有关导致共传输器的信号的信息 位于某些上皮细胞的顶端质膜中，并位于 其他上皮细胞的基侧质膜。

Myo-inositol is an abundant sugar present in all cells. It has two very important functions: 1) It is a precursor of phosphatidylinositol, an important component of the plasma membrane of all cells, and 2) it is a compatible osmolyte, i.e.-in contrast to sodium and potassium, its intracellular concentration can increase 10 fold without disturbing cell function. Although the concentration of myo-inositol in plasma is 0.05mM, its concentration in most cells is lO-2OmM. It enters cells against such a steep concentration gradient on a sodium/myo-inositol cotransporter that is driven by the electrochemical gradient for sodium. Although intracellular deficiency of myoinositol has been implicated in the neuropathy and nephropathy of diabetes mellitus, virtually nothing is known about the cotransporter or its regulation. This project is designed to gain an understanding of the function and regulation of the sodium/myo-inositol cotransporter by cloning and sequencing its cDNA from cultured kidney cells, that like the renal medulla, raise their myo-inositol levels to >80mM in response to hypertonicity. At that time, there is increased cotransporter activity, some evidence for increased mRNA for the cotransporter. The cDNA will be sequenced to reveal the primary structure of the cotransporter and facilitate the production of antibodies against it. The antibodies will be used to quantify the number of cotransporters in renal cells in order to determine whether the cells accumulate more myo-inositol because there are more cotransporters, and if there are more, whether that is due to increased synthesis and/or decreased degradation of the cotransporter. The cDNA will be used to construct an RNA probe to measure cell mRNA levels for the cotransporter to determine whether there is in fact an increase in cotransporter mRNA and whether synthesis and/or degradation of the mRNA is regulated. If mRNA synthesis is increased, the gene for the cotransporter will be cloned so that the mechanism of regulation hypertonicity and by other factors can be studied. The cDNA will be used to develop probes to clone the cDNA for sodium/ myo-inositol cotransporters located in the apical plasma membrane of kidney and small intestines where it functions to transport myo-inositol from lumen to blood. The sequence data should yield information about the signal that results in the cotransporter being located in the apical plasma membrane of some epithelia and in the basolateral plasma membrane of other epithelia.