MOLECULAR COEVOLUTION OF GROWTH HORMONE AND ITS RECEPTOR

我们的目标是利用哺乳动物生长激素(GH)及其受体 (GHR)作为研究分子过程和机理的模型系统 共同进化，并了解GH-GHR相互作用的分子基础。 哺乳动物GHS和GHR表现出高度的多样性和物种特异性。 例如，人类生长激素和生长激素受体具有独特的特征：(1)人类生长激素 在序列上与非灵长类GHS有很大的不同。(2)人生长激素刺激 非灵长类动物的生长，而非灵长类GHS在人类中不活跃 (称为人类GHR的物种特异性)。(3)非灵长类哺乳动物 只有一个生长激素基因，而人类有5个类似生长激素的基因。奇特 生长激素和生长激素受体的特征也在其他哺乳动物中发现，如老鼠， 老鼠和牛。特别是，豚鼠GHR不与人结合 (或牛)生长激素，豚鼠即使在没有生长激素的情况下也生长良好。 为了理解这些和其他特征，我们需要研究分子 生长激素-生长激素相互作用的基础。我们建议进行以下工作 工作，使用分子、生物化学、进化和 统计方法：1.确定生长激素和类生长激素的数量 Galago，Tarsier，松鼠猴和豚鼠的基因。数列 这些物种中的GH和GH样基因以及几个物种中的GH基因 灵长类动物和豚鼠。2.测序半乳鼠的GHR基因， 松鼠猴(部分还包括其他高等灵长类动物)， 兔子和豚鼠。3.表达生长激素及其结合蛋白(GHBP) 来自不同物种的DNA。4.确定GH和GHR中符合以下条件的站点 潜在的重要功能，并执行特定的突变以 产生变种人。5.在竞争中使用不同的GHS和GHBPS 结合分析以确定每个变化的效果。对于氨基酸 观察到的对结合的显著影响的差异，确定 它们在组合中的集体效应。6.进行统计 对数据进行分析以描述生长激素和生长激素的进化。

Our goals are to use the mammalian growth hormone (GH) and its receptor (GHR) as a model system to study the process and mechanisms of molecular coevolution and to understand the molecular basis of GH-GHR interaction. Mammalian GHs and GHRs exhibit large diversity and species specificity. For example, human GH and GHR have peculiar features: (1) Human GH differ greatly in sequence from nonprimate GHs. (2) Human GH stimulates growth in nonprimates, whereas nonprimate GHs are inactive in humans (known as the species specificity of human GHR). (3) Nonprimate mammals have only one GH gene, whereas humans have 5 GH-like genes. Peculiar features of GH and GHR are also found in other mammals such as rat, mouse, and cow. In particular, guinea pig GHR does not bind to human (or bovine) GH, and guinea pigs grow well even in the absence of GH. To understand these and other features, we need to study the molecular basis of the GH-GHR interaction. We propose to pursue the following work, using a combination of molecular, biochemical, evolutionary, and statistical approaches: 1. Determine the numbers of GH and GH-like genes in the galago, tarsier, squirrel monkey, and guinea pig. Sequence the GH and GH-like genes in these species and the GH gene in several primates and the guinea pig. 2. Sequence the GHR gene in the galago, tarsier, squirrel monkey (and, partially, other higher primates), the rabbit, and guinea pig. 3. Express GH and GH binding protein (GHBP) cDNAs from various species. 4. Identify sites in GH and GHR that are potentially functionally important and perform specific mutagenesis to generate mutants. 5. Use the variant GHs and GHBPs in competitive binding assays to determine the effect of each change. For amino acid differences with observed significant effects on binding, determine their collective effect in combinations. 6. Conduct statistical analyses of data to characterize evolution of GH and GHR.