Structure and Function of the LH, FSH, and TSH Receptors

促黄体生成素、卵泡刺激素和促甲状腺激素受体，统称为糖蛋白激素受体(GPH-R‘s)， 包括一个独特的视紫红质样G蛋白偶联受体(GPCR)亚家族。他们各自都是 由结合激素的大胞外域和七个跨膜(TM)域组成， 与G蛋白结合，主要是G蛋白。这些受体中的每一个的激活状态都是由 荷尔蒙的结合或通过离散的突变而引起的结构性活动。这笔赠款的目的是 确定GPH-R激活的结构基础。通常，我们将使用两个实验 方法，每一种方法都将与分子建模相结合。第一种方法是利用破坏性的 和相互突变来检验这一假设，即在三个物种中高度保守的TM残基 GPH-R参与螺旋间相互作用，稳定静息状态下的受体。第二 该方法使用来自给定物种或来自特定物种的不同GPH-R之间的选择性嵌合体突变 给出不同物种的GPH-R，以检验某些不同的TM残基调制 影响螺旋间相互作用的GPH-R的活性。尽管氨基酸含量很高 在GPH-R的TM区中，某些GPH-R对表现出明显不同程度的 基础活性、突变诱导或激素诱导的激活。通过交换发散的TM残基 在两个性质不同的相关GPH-R之间，我们可以保持受体的整体完整性 (因为发散残基能够维持整体结构)并确定精确的 具有较高或较低活性的氨基酸。计算机建模将与 这些实验策略中的每一个都有助于数据解释和定义螺旋间的相互作用 在静息状态、突变诱导的活动状态和激素稳定状态下稳定GPH-R 活动状态。这项建议的具体目的是：1.确定在保护植物残留物方面的作用 GPH-R在维持受体的静息状态方面具有重要作用。2.确定经济增长的结构基础 不同程度的GPH-R的静止态的构造活性。3.确定结构 通过激活使GPH-R的不同磁化率稳定在活性状态的基础 突变。4.通过以下方式确定激素刺激Gs不同程度激活的结构基础 GPH-R的。

The LH, FSH and TSH receptors, collectively known as the glycoprotein hormone receptor (GPH-R's), comprise a unique subfamily of rhodopsin-like G protein-coupled receptors (GPCR's). They are each composed of a large extracellular domain that binds hormone and a seven transmembrane (TM) domain that couples to G proteins, primarily Gs. The active states of each of these receptors are stabilized by the binding of hormone or by discrete mutations that induce constitutive activity. The aims of this grant are to determine the structural basis for the activation of the GPH-R's. In general, we will use two experimental approaches, each of which will be coupled with molecular modeling. The first approach utilizes disruptive and reciprocal mutagenesis to test the hypothesis that TM residues that are highly conserved in the three GPH-R's participate in interhelical interactions that stabilize the receptors in the resting state. The second approach uses selective chimera mutagenesis between different GPH-R's from a given species or from a given GPH-R of different species to test the hypothesis that certain divergent TM residues modulate the activities of the GPH-R's by affecting interhelical interactions. In spite of the high degree of amino acid identity in the TM regions of the GPH-R's, certain pairs of GPH-R's exhibit markedly different degrees of basal activity, mutation-induced, or hormone-induced activation. By interchanging the divergent TM residues between two related GPH-R's with differing properties, we can maintain the overall integrity of the receptor (because the divergent residues are capable of maintaining the overall structure) and determine the precise amino acids that confer the greater or lesser degree of activity. Computer modeling will be coupled with each of these experimental strategies to aid in data interpretation and to define those interhelical interactions that stabilize the GPH-R's in the resting states, in mutation-induced active states, and in hormone-stabilized active states. The specific aims of this proposal are: 1. Determine the roles that conserved residues of the GPH-R's have in maintaining the resting states of the receptors. 2. Determine the structural basis for the different degrees of constitutive activity of the resting states of the GPH-R's. 3. Determine the structural basis for the different susceptibilities of the GPH-R's to be stabilized in an active state by activating mutations. 4. Determine the structural basis for the different degrees of hormone-stimulated Gs activation by GPH-R's.