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)作为研究分子生物学过程和机制的模型系统， 共同进化和了解GH-GHR相互作用的分子基础。 哺乳动物生长激素和生长激素受体表现出很大的多样性和物种特异性。 例如，人GH和GHR具有独特的特征：（1）人GH 在序列上与非灵长类GH有很大不同。(2)人GH刺激 生长在非灵长类动物，而非灵长类动物生长激素是不活跃的人类 （称为人类GHR的种属特异性）。(3)非灵长类哺乳动物 只有一个GH基因，而人类有5个类似GH的基因。 奇特 GH和GHR的特征也在其它哺乳动物如大鼠中发现， 老鼠和奶牛 特别地，豚鼠GHR不与人GHR结合。 (or牛）GH，豚鼠生长良好，即使在没有GH的情况下。 为了了解这些和其他特征，我们需要研究分子 GH-GHR相互作用的基础。 我们建议采取以下措施 工作，使用分子，生物化学，进化和 统计方法：1. 确定GH和GH样的数量 大羚羊眼镜猴松鼠猴和豚鼠的基因 序列 这些物种中的GH和GH样基因以及一些物种中的GH基因， 灵长类动物和豚鼠。 2. 对盔猴的生长激素受体基因进行测序， 眼镜猴，松鼠猴（以及部分其他高等灵长类动物）， 兔子和豚鼠。 3. 表达GH和GH结合蛋白（GHBP） 来自不同物种的cDNA。 4.确定GH和GHR中 潜在的功能重要性，并进行特异性诱变， 产生突变体。5. 在竞争中使用变体GH和GHBPs 结合试验以确定每种变化的影响。 对于氨基酸 与观察到的对结合的显著影响的差异，确定 它们的组合效应。 6. 进行统计 分析数据以表征GH和GHR的演变。

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.