The Regulation of Glucose Transport by Insulin

描述：（由申请人提供）胰岛素刺激葡萄糖摄取， 肌肉和脂肪组织通过易位的胰岛素反应 葡萄糖转运蛋白4（GLUT 4）从细胞内区室到 细胞表面虽然这种易位事件需要激活 磷脂酰肌醇3-激酶（PI 3-激酶）是不够的，这意味着 第二信号通路。PI 3-激酶非依赖性途径涉及 原癌基因c-cbl通过接头的酪氨酸磷酸化 蛋白cbl相关蛋白（CAP）。CAP/cbl的下游效应子 在该途径中最常见的是畸胎瘤10（TC 10），其为GTP酶的Rho家族的成员。 克隆#38被发现是一种与突触融合蛋白相互作用的蛋白质。 4-相互作用蛋白（synip）在酵母双杂交筛选。Synip是一个 突触融合蛋白4的负调节因子，GLUT 4囊泡对接在 质膜有趣的是，这部小说 与TC 10相互作用的RhoGAP结构域。此外还 具有PX和SH 3蛋白相互作用结构域， 信号分子的结合。因此，我们的假设是，克隆#38是一个 一种将胰岛素信号分子募集到 GLUT 4囊泡对接。为了验证这一假设，我将首先从生物化学的角度 表征克隆#38与Synip和TC 10的相互作用。缺失突变体， 未能与Synip或TC 10相互作用将用于特定目标2，以评估 克隆#38在胰岛素刺激葡萄糖摄取和GLUT 4中的作用 易位在具体目标3中，我将寻找与 克隆#38的PX和SH 3结构域。这种方法可能会导致新的见解 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.