Evolution of pituitary hormones

我们克隆了编码鸡和日本鹌鹑的促黄体生成激素（LH）β亚基，日本鹌鹑的促卵泡激素β亚基和日本鹌鹑，牛蛙，蟾蜍和澳大利亚肺鱼的α亚基的前体分子的cDNAs。利用这些数据和其他脊椎动物物种的数据，我们比较了脊椎动物物种之间的分子的一级结构。α亚基的一级结构高度保守，β亚基的一级结构保守性较差。我们还预测了这些促性腺激素和促甲状腺激素的α和β亚基的二级结构。这两个亚基在脊椎动物种间具有很好的一致性。我们的结论是，在脊椎动物的三维结构是更高度保守的比一级结构。我们构建了一个促性腺激素和促甲状腺激素β亚基的基因树。促卵泡激素与促甲状腺激素的关系比促黄体激素更为密切。这与促性腺激素/促甲状腺激素家族成员的经典分组不同，其中促卵泡激素和促黄体激素过去被归类为促性腺激素，促甲状腺激素与促性腺激素分开。我们还发现，澳大利亚肺鱼的α亚基是更密切相关的四足脊椎动物的α亚基比硬骨鱼。在神经垂体激素前体分子中也得到了类似的结果。

We have cloned cDNAs encoding precursor molecules of luteinizing hormone (LH) beta subunits of the chicken and Japanese quail, the beta subunit of follicle-stimulating hormone of Japanese quail and alpha subunits of the Japanese quail, bullfrog, toad and Australian lung-fish. Using these data and data of other vertebrate species reported, we compared the primary structure of the molecules among vertebrate species. The primary structure of the alpha subunits was highly conserved and that of the beta subunits was less conserved. We also predicted the secondary sturctures of the alpha and beta subunits of these gonadotropins and thyrotropins. It was very well coincided among vertebrate species in both subunits. We concluded that the three dimensional structure is more highly conserved than the primary structure in vertebrates. We constructed a phylogenic tree of the beta subunits of gonadotropins and thyrotropin. It was found that follicle-stimulating hormone is more closely related to thyrotropin than luteinizing hormone. This is different from the classic grouping of members of the gonadotropin/thyrotropin family in which follicle-stimulating hormone and luteinizing hormone used to be categorized together as gonadotropin and thyrotropin was separated from gonadotropin. We also found that the alpha subunit of Australian lung-fish is more closely related to alpha subunits of tetrapod vertebrates than to those of teleosts. A similar result was obtained in neurohypophyseal hormone precursor molecules.