TETRASPAN PROTEINS AND REGULATION OF RENAL ION TRANSPORT

越来越多的证据表明，肾离子转运系统的细胞生物学和生理学特性部分是通过它们与各种调节蛋白和结构蛋白的相互作用来确定的。我们已经证明，肾离子转运多肽相互作用与tetraspan蛋白，在体外和原位。正如其名称所暗示的，tetraspan家族的成员是预测具有四个跨膜区段的跨膜蛋白。基因组测序数据表明，哺乳动物表达约30个tetraspan家族， 成员所有这些的特征在于面向细胞质的短N和C末端尾和两个相对大的细胞外环，其中发现了许多保守残基，其构成存在于大多数tetraspan家族成员中的分子标记。虽然已经了解了很多关于tetraspan蛋白的表达模式，但对其功能知之甚少。已经证明，tetraspans与许多跨膜蛋白形成大分子复合物。这些关联可能参与调节膜蛋白 分布、稳定性和获得调节分子。我们发现与tetraspans的相互作用可以对肾转运蛋白的亚细胞定位产生影响。因此，与tetraspan蛋白CD63的相互作用诱导H，K-ATP酶的快速内吞作用。相反，与四跨膜蛋白样蛋白VIP 17/MAL的结合阻止了水通道蛋白2水通道的内化，并增加了其在质膜上的功能存在。我们将研究tetraspan蛋白在调节细胞凋亡中的作用。 许多重要的肾脏转运系统的分布和功能。为此，我们将定义与肾离子转运蛋白的选定子集的每个个体成员相关的tetraspan伙伴的概况。我们将评估这些协会对这些运输系统的生理特性的影响，我们将定义分子结构域的tetraspan和运输蛋白参与特定的相互作用。最后，我们将利用基因敲除小鼠模型来测量tetraspan的影响。 相互作用对肾脏原位转运过程的影响。

There is growing evidence that the cell biologic and physiologic properties of renal ion transport systems are determined in part through their interactions with a variety of regulatory and structural proteins. We have demonstrated that renal ion transport polypeptides interact with tetraspan proteins, both in vitro and in situ. As their name implies, members of the tetraspan family are transmembrane proteins that are predicted to possess four membrane spanning segments. Genomic sequencing data suggest that mammals express about 30 tetraspan family members. All of these are characterized by short N and C terminal tails facing the cytoplasm and two relatively large extracellular loops in which are found a number of conserved residues that constitute a molecular signature present in most tetraspan family members. While much has been learned about the expression patterns of tetraspan proteins, less is known of their functions. It has been demonstrated that tetraspans form macromolecular complexes with a number of transmembrane proteins. These associations may be involved in regulating membrane protein distribution, stability and access to regulatory molecules. We find that interactions with tetraspans can exert tramatic effects on the subcellular localizations of renal transport proteins. Thus, interaction with the tetraspan protein CD63 induces the rapid endocytosis of the H,K-ATPase. In contrast, association with the tetraspan-like protein VIP17/MAL prevents the internalization of the aquaporin 2 water channel and increases its functional presence at the plasma membrane. We will examine the role that tetraspan proteins play in regulating the distribution and function of a number of important renal transport systems. Towards this end we will define the profile of tetraspan partners that associate with each of the individual members of a selected subset of renal ion transport proteins. We will assess the impact of these associations on the physiologic properties of these transport systems and we will define molecular domains of the tetraspan and transport proteins that participate in specific interactions. Finally, we will take advantage of knockout mouse models to measure the impact of tetraspan interactions on renal transport processes in situ.