The Regulation of Glucose Transport by Insulin

描述：(申请人提供)胰岛素刺激葡萄糖摄取 肌肉和脂肪组织通过胰岛素反应性移位 葡萄糖转运蛋白4(GLUT4)从细胞内的一个隔室到 细胞表面。尽管此移位事件需要激活 磷脂酰肌醇3-激酶(PI-3-激酶)是不够的，这意味着 第二条信号通路。PI3-激酶非依赖性途径涉及 原癌基因c-cbl通过接头酪氨酸的磷酸化 蛋白。CBL相关蛋白(CAP)。CAP/CBL的下游效应器 途径是畸胎癌10(TC10)，是Rho家族GTP酶的成员。 克隆#38被发现是一种与合成素相互作用的蛋白质 酵母双杂交筛选中的4-相互作用蛋白(SYIP)。Synip是一家 合成素4的负调节因子，它是GLUT4囊泡停靠在 质膜。有趣的是，这部小说 蛋白质具有与TC10相互作用的RhoGAP结构域。此外，它还 具有Px和SH3蛋白相互作用结构域，这些结构域对 信号分子的结合。因此，我们的假设是，克隆人#38是一个 一种支架蛋白，可将胰岛素信号分子招募到 GLUT4囊泡对接。为了验证这一假设，我将首先用生物化学方法 描述克隆#38与Synip和TC10的交互作用。缺失突变体 未能与SYIP交互或TC10将在特定目标2中使用以评估 克隆38在胰岛素刺激的葡萄糖摄取和GLUT4中的作用 易位。在特定的目标3中，我将搜索与 克隆#38的Px和SH3结构域。这种方法可能会带来对 胰岛素作用的分子机制。

DESCRIPTION: (Provided By Applicant) Insulin stimulates glucose uptake into muscle and adipose tissue through the translocation of the insulin-responsive glucose transporter type 4 (GLUT4) from an intracellular compartment to the cell surface. Although this translocation event requires the activation of phosphatidylinositol 3-kinase (PI 3-kinase) it is not sufficient, implicating a second signaling pathway. The PI 3-kinase-independent pathway involves the tyrosinc phosphorylation of the proto-oncogene c-cbl through the adaptor protein. cbl-associated protein (CAP). A downstream effector of the CAP/cbl pathway is teratocareinoma 10 (TC 10), a member of the Rho family of GTpases. Clone#38 was discovered as a protein that interacts with the syntaxin 4-interacting protein (synip) in a yeast two-hybrid screening. Synip is a negative regulator of syntaxin 4, the receptor for GLUT4 vesicle docking at the plasma membrane. Interestingly, this novel protein posses a RhoGAP domain that interacts with TC10. In addition, it also possesses a PX and SH3 protein interaction domains that are important for binding of signaling molecules. Thus, our hypothesis is that clone#38 is a scaffolding protein that recruits insulin signaling molecules to the site of GLUT4 vesicle docking. To test this hypothesis, I will first biochemically characterize clone#38 interaction with synip and TC10. Deletional mutants that fail to interact with synip or TC10 will be used in specific aim 2 to evaluate the role of clone#38 in insulin-stimulated glucose uptake and GLUT4 translocation. In specific aim 3, I will search for proteins that bind to the PX and SH3 domains of clone#38. This approach may lead to new insights into the molecular mechanism of insulin action.