THE MOLECULAR-BIOLOGY OF AVIAN GONADOTROPIN
THE MOLECULAR-BIOLOGY OF AVIAN GONADOTROPIN
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DOI：
10.3382/ps.0720856
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发表时间：
1993-05-01
期刊：
影响因子：
4.4
通讯作者：
ISHII, S
中科院分区：
文献类型：
--
作者：
ISHII, S
鸡和鹌鹑促性腺激素（LH）β亚基前体分子的互补DNA已被克隆。从cDNA的核苷酸序列，推导出这些鸟类LH β亚基分子的一级结构。一级结构相似，氨基酸序列同源性为91.6%。对于α亚基，也在这两种鸟类中进行了cDNA克隆。预测的这些鸟类的α亚基分子的一级结构是完全相同的，虽然它们的cDNA的核苷酸序列略有不同。两种鸟的LH β亚基分子在相同的位置有15个Pro残基。其中10个与哺乳动物LH β亚基中的Pro残基位置相同，约有20个Pro残基。利用蛋白质工程的计算机程序预测了鸡LH β亚基分子的二级结构和每个氨基酸残基的暴露量。结果表明，15个Pro残基中的大多数不存在于预测β结构的区域，而是分布在预测转角或环的区域。此外，预测四个Tyr残基中的三个位于分子内部。这些结果表明，预测的二级结构的环中的Pro残基的数量的存在是高动物组和激素特异性的LH-LH受体相互作用的原因。预测的Tyr残基的内部定位被认为是通过常规放射性碘化程序引起受体结合活性的损失。
Complimentary DNA for precursor molecules of chicken and quail luteinizing hormone (LH) beta subunits have been cloned. From nucleotide sequences of the cDNA, the primary structures of the LH beta subunit molecules of these avian species were deduced. The primary structures were similar, the amino acid sequence homology being 91.6%. For the alpha subunit, cloning of cDNA has been performed also in these two avian species. Predicted primary structures of the alpha subunit molecules of these birds were completely identical, although nucleotide sequences of their cDNA were slightly different. The LH beta subunit molecules of both birds had 15 Pro residues at the same positions. Ten of them shared the same positions with Pro residues in the mammalian LH beta subunits, in which about 20 Pro residues exist. Prediction of the secondary structure and exposure of each amino acid residue in the chicken LH beta subunit molecule were performed with the aid of a computer program for protein engineering. It was revealed that most of 15 Pro residues did not exist in regions where the beta structure was predicted but were distributed in regions where a turn or loop was predicted. In addition, three of four Tyr residues were predicted to be located inside the molecule. These results suggest that the predicted presence of a number of Pro residues in the loop of the secondary structure is a cause of high animal group and hormone specificities in the LH-LH receptor interaction. The predicted internal localization of Tyr residues is considered to cause loss of receptor binding activity by conventional radioiodination procedures.