大通牦牛LF基因的克隆与分子特征

Cloning and molecular characteristics of Datong yak's LF gene

通过RT-PCR克隆了牦牛包含LF基因编码区的cDNA序列(GenBank登录号为EU547251);将克隆获得的LF基因的cDNA与乳牛相应序列进行了比对;对牦牛LF蛋白的氨基酸序列(GenBank登录号为ACB29794)与其他物种的相应序列进行了比较,应用在线生物软件对牦牛LF蛋白的特性和结构进行了预测。结果表明,克隆获得的牦牛LF基因cDNA片段长度为2 344 bp,其中LF基因编码区全长2 124bp,编码708个氨基酸;克隆获得的牦牛cDNA序列与乳牛该序列存在15个碱基的变异;各物种LF蛋白具有较高的同源性,LF蛋白进化树符合物种进化规律;牦牛LF蛋白含有α-螺旋36.0%、β-折叠22.4%、β-转角31.1%、无规卷曲12.9%;同源建模预测的LF 3D模型显示,LF为多肽链在二级结构基础上折叠形成的2个极相似的、对称的球状叶,即N叶和C叶,中间由一段对蛋白酶敏感的α-螺旋连接,呈"二枚银杏叶型"结构。

A cDNA sequence containing coding region of LF gene of yak was cloned by RT-PCR and compared to corresponding sequences of cow. The sequences were analysed in yak and other species. Using online biological softwares,the structure and properties of LF protein of yak were predicted. The 2 344 bp cDNA of LF gene of yak was cloned,and the length of coding region of LF gene was 2 124 bp,encoding 708 amino acids. There were 15 mutations in the cDNA between yak and cow. There was high homology of LF protein among different species. The evolutionary tree of all species complies with laws of evolution. There was 36.0% alpha helix,22.4% extended strand,31. 1% beta turn, 12. 9% random coil in LF protein of yak. Homogenous 3D model of LF by predict showed that LF protein formed two similar and symmetrical leaves,namely N-leaf and C-leaf connected by an alpha helix impressionable to proteinase, and LF protein presented ＂two-folium-ginkgo-shaped＂ structure.