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

LH、FSH和TSH受体，统称为糖蛋白激素受体（GPH-R）， 包括视紫红质样G蛋白偶联受体（GPCR）的独特亚家族。它们各自 由结合激素的大细胞外结构域和 与G蛋白结合主要是G蛋白这些受体中的每一种的活性状态都是由 结合激素或通过诱导组成型活性的离散突变。该补助金的目的是 确定GPH-R激活的结构基础。一般来说，我们将使用两个实验 方法，其中每一个都将与分子建模相结合。第一种方法是利用破坏性 和相互诱变，以测试这三个中高度保守的TM残基的假设， GPH-R参与螺旋间相互作用，使受体稳定在静息状态。第二 一种方法是在来自给定物种或来自同一物种的不同GPH-R之间使用选择性嵌合诱变。 给定不同物种的GPH-R，以检验某些不同的TM残基调节 GPH-R的活性通过影响螺旋间的相互作用。尽管氨基酸含量很高， 由于GPH-R的TM区域中的同一性，某些GPH-R对表现出明显不同程度的 基础活性、突变诱导的或突变诱导的激活。通过交换不同的TM残基 在两个具有不同性质的相关GPH-R之间，我们可以保持受体的整体完整性 （因为趋异残基能够保持整体结构）并确定精确的 赋予或多或少活性的氨基酸。计算机建模将与 这些实验策略中的每一个都有助于解释数据，并定义那些螺旋间的相互作用， 稳定GPH-R的静止状态，在突变诱导的活性状态， 活跃的国家。该提案的具体目标是：1.确定保守残基的作用， GPH-R在维持受体的静息状态方面起着重要作用。2.确定结构基础， GPH-R的静息状态的不同程度的组成活性。3.确定结构 GPH-R的不同亲和性通过活化而稳定在活性状态的基础 突变。4.通过以下方式确定不同程度的葡萄糖刺激的Gs激活的结构基础： GPH-R

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.