MOLECULAR MECHANISMS OF INSULIN RECEPTOR KINASE FUNCTION

描述：胰岛素受体是胰岛素家族中具有决定性意义的成员。 蛋白质(酪氨酸酶)。这个家族包括胰岛素受体- 像生长因子，肝细胞生长因子，以及果蝇 Seven less、ROS和UR2转化癌基因。定义 分子特征是由三种酪氨酸组成的保守簇 该酶的催化核心。这些酪氨酸的自动磷酸化 导致底物磷酸化的激活。此激活是 对这些酶的生物学功能至关重要。然而， 每个家族成员的激酶结构域都具有唯一性 与其各自独特的相关的自动磷酸化位点 细胞功能。通过这个家族的信号转导 受体依赖于细胞环境和受 生长因子或激素。前者是对生物性的允许 作用，而后者是必需的，以提高从一个基础 变为激活状态。该激酶至少有四个特定的特征 结构域是这种激活过程所固有的，并因此对信号 转导：1.激活该激酶的“核心”自动磷酸化， 2.每种激酶的“亚区”自磷酸化特性， 单独或共同导致3.接头蛋白的识别，以及 4.底物的磷酸化。 因此，这些受体的信号转导的顶点是激活。 激活域的。其总体目标是了解 基态和活化态之间的分子差异 由自身磷酸化激活的酪氨酸激酶。具体的 这项建议的目的是研究(1)分子机制 将核心酪氨酸的自动磷酸化与激酶联系起来 激活，以及(2)调节独特的反应的机制 自动磷酸化位点。每个机制都包含一组 保守的调控基序，可以在分子水平上理解 通过合理设计的诱变来达到这个水平。运动学和物理学- 然后，化学测量将揭示催化事件和 对于激活是必要和充分的构象变化。 这项工作的早期阶段主要集中在分离的细胞质激酶上 胰岛素受体的结构域，它更容易被 拟议的动力学和物理研究。长期目标是 通过激活域的相互作用重建激活 跨膜β亚基，并最终建立分子 胰岛素与α-亚基结合激活的机制 完整的受体。

DESCRIPTION: The insulin receptor is the defining member of a family of protein(tyrosine) kinases. This family includes receptors for insulin- like growth factor, and hepatocyte growth factor, as well as Drosophila sevenless, Ros, and the UR2 transforming oncogene. The defining molecular feature is a conserved cluster of three tyrosines within the catalytic core of the kinase. Autophosphorylation of these tyrosines leads to activation of substrate phosphorylation. This activation is essential to the biological function of these kinases. However, the kinase domain of each family member is distinguished by unique autophosphorylation sites that are related to their respective unique cellular functions. Signal transduction through this family of receptors depends on the cellular environment and stimulation by the growth factor or hormone. The former is permissive of the biological effects, and the latter is necessary to raise the kinase from a basal to an activated state. At least four specific features of the kinase domain are intrinsic to this process of activation and thus to signal transduction: 1. "core" autophosphorylation that activates the kinase, 2. "subdomain" autophosphorylation characteristic of each kinase, which separately or together lead to 3. recognition of adapter proteins, and 4. phosphorylation of substrates. Thus, the apex of signal transduction for these receptors is activation of the kinase domain. The broad objective is to understand the molecular differences between basal and activated states of these tyrosine kinases that are activated by autophosphorylation. The specific objectives of this proposal are to examine (1) the molecular mechanisms that link autophosphorylation of the core tyrosines to kinase activation, and (2) the mechanisms that regulate reaction of the unique autophosphorylation sites. Each mechanism encompasses a set of conserved regulatory motifs that can be understood at the molecular level through rationally designed mutagenesis. Kinetics and physical- chemical measurements will then reveal both the catalytic events and conformational changes that are necessary and sufficient for activation. The early stages of this work focus on the isolated cytoplasmic kinase domain of the insulin receptor, which is more accessible for the proposed kinetic and physical studies. The long-term goals are to reconstruct activation via kinase domain interactions between transmembrane beta-subunits, and ultimately to establish the molecular mechanism of activation by insulin through binding to the alpha-subunit of the intact receptor.