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。他们每个人 由一个结合激素的大细胞外结构域和一个七跨膜 (TM) 结构域组成 与 G 蛋白（主要是 Gs）偶联。这些受体的活性状态均由以下因素稳定： 激素结合或通过诱导组成型活性的离散突变。这笔赠款的目的是 确定 GPH-R 激活的结构基础。一般来说，我们会使用两个实验 方法，每种方法都将与分子建模相结合。第一种方法利用破坏性 和相互诱变来检验TM残基在这三个中高度保守的假设 GPH-R 参与螺旋间相互作用，使受体稳定在静息状态。第二个 方法使用来自给定物种或来自特定物种的不同 GPH-R 之间的选择性嵌合诱变 给定不同物种的 GPH-R 来检验某些不同的 TM 残基调节的假设 通过影响螺旋间的相互作用来控制 GPH-R 的活性。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 对表现出明显不同的程度 基础活性、突变诱导或激素诱导的激活。通过交换不同的 TM 残基 在两个具有不同特性的相关 GPH-R 之间，我们可以保持受体的整体完整性 （因为不同的残基能够维持整体结构）并确定精确的 赋予较大或较小活性程度的氨基酸。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相互作用 使 GPH-R 在静息状态、突变诱导的活性状态和激素稳定状态下保持稳定 活跃状态。该提案的具体目标是： 1. 确定保留残基的作用 GPH-R 具有维持受体静息状态的作用。 2. 确定结构基础 GPH-R 静息状态下不同程度的组成活性。 3.确定结构 GPH-R 的不同敏感性通过激活而稳定在活性状态的基础 突变。 4. 确定不同程度的激素刺激 Gs 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.