摘要： 为研究牦牛胰岛素样生长因子1受体基因（IGF-IR）的结构和功能，采用同源克隆和RT-PCR方法分段扩增牦牛IGF-IR，拼接获得全长序列，利用生物学软件进行分析。结果表明，牦牛IGF-IR基因ORF长约4 104 bp，编码1 367个氨基酸；理论分子量约154.95 ku，等电点pI值约5.71。与黄牛IGF-IR比较，牦牛IGF-IR基因序列有20处碱基改变，其中G到T碱基颠换2次，G到A碱基转换2次，C到T碱基转换7次，A到G碱基转换3次，T到C碱基转换6次，以及3个位点氨基酸改变（G6R、T29I和S30I）。系统进化分析表明，牦牛与黄牛、猪、人、狗、小鼠、猩猩等物种IGF-IR氨基酸相似性均大于92%，处于同一进化分支，具有高度同源性。蛋白结构预测表明，牦牛IGF-IR包含半胱氨酸富集区（FU）、纤连蛋白Ⅲ型结构域（FN3）、跨膜结构域（TM）及酪氨酸蛋白激酶区（TyrKc），具有该受体家族的特征结构域。同源建模表明，其成熟区段氨基酸序列与人的IGF-IR有98.68%的相似性。为后续牦牛IGF-IR基因的功能研究奠定了基础。

关键词: 牦牛, IGF-IR基因, 克隆, 序列分析

Abstract: The complete cDNA encoding yak insulin like growth factor 1 receptor (IGF-IR) gene was cloned with RT-PCR and homologous cloning methods. Sequence analysis showed that the entire coding region was 4 104 bp in length encoding 1 367 amino acids with a putative mass of 154.95 ku and pI of 5.71. Compared to IGF-IR gene sequence from cattle, there were 20 base changes in yak IGF-IR gene, including 2 substitutions for G-T, 2 transitions for G-A, 7 transitions for C-T, 3 transitions for A-G and 6 transitions for T-C, respectively. In addition, amino acid changed at 3 sites (G6R, T29I and S30I). The phylogenetic analysis revealed that yak IGF-IR gene had high homology (> 92%)with that of cattle, pig, human, dog, mouse and chimpamzee, which were classified into the same branch. The secondary structure predication indicated that yak IGF-IR protein might have the typical domains of the IGF-IR family, containing the furin-like cysteine rich region (FU), fibronectin type Ⅲ domain (FN3), transmembrane domain (TM), and tyrosine kinase domain (TyrKc), respectively. 3D model showed the mature fragment in yak IGF-IR had 98.68% homology with human IGF-IR. The present results provided the valuable foundation for further studies on yak IGF-IR functions.

Key words: Yak, IGF-IR gene, Cloning, Sequence analysis

中图分类号: 

• Q78

• S823