绵羊IGF-Ⅰ和IGF-Ⅰ R基因特征分析及其在肌肉组织中的表达差异

Bioinformatics analysis on IGF-ⅠandIGF-Ⅰ R genes and their different expression in muscle tissue of sheep

为了比较IGF-Ⅰ和IGF-ⅠR基因在绵羊肌肉中的表达差异,根据GenBank公布的绵羊IGF-Ⅰ和IGF-ⅠR基因mRNA序列设计特异性引物,采用实时定量PCR方法检测其在甘肃‘高山细毛羊’及其与南非肉用‘美利奴’杂交F1代（南甘F1代）羔羊肌肉组织中的表达量.利用生物信息学软件分析了绵羊IGF-Ⅰ和IGF-ⅠR基因结构,并构建系统进化树,探讨了其生物学功能.结果表明：南甘F1代羔羊肌肉组织中IGF-Ⅰ基因的表达量显著高于‘甘肃高山细毛羊’（P〈0.05）,而IGF-ⅠR基因的表达量在南甘F1代羔羊和‘甘肃高山细毛羊’肌肉组织中没有显著变化（P〉0.05）.绵羊IGF-Ⅰ和IGF-ⅠR基因分别含有465bp和4 518bp的完整开放阅读框,编码154个和1 505个氨基酸;其蛋白质分子量分别为17 011.71U和169 267.26U,等电点分别为9.36和6.70;IGF-Ⅰ基因信号肽切割点分别位于49～50位氨基酸之间,而IGF-ⅠR基因不含信号肽;IGF-Ⅰ基因编码产物的二级结构主要以无规则卷曲和α-螺旋为主,位于细胞核的可能性最高（62.5%）;IGF-ⅠR基因编码产物的二级结构主要以无规则卷曲为主,位于细胞质的可能性最高（34.8%）;IGF-Ⅰ和IGF-ⅠR基因分别作为激素和信号传感器参与机体生物学过程.

In order to compare the different expression of IGF-ⅠandIGF-ⅠR genes in muscle tissue of two sheep breeds,‘Gansu Alpine Merino＇and its F1 hybrids with ‘South African Meat Merino＇,different primers were designed according to the mRNA sequences of these two genes in GeneBank,and their expression quantity was determined by real-time quantitative PCR.The structure and function of the IGF-Ⅰand IGF-ⅠR gene-encoded protein were predicted by the bioinformatics software and the phylogenetic trees ofthese two genes were constructed.The results showed that：IGF-Ⅰgene expression quantity in muscle tissue of the F1 hybrids was significantly higher than that of‘Gansu Alpine Merino＇（P〈0.05）,while IGF-ⅠR gene expression quantity in muscle tissue showed no difference between the F1 hybrids and‘Gansu Alpine Merino＇（P〉0.05）.IGF-ⅠandIGF-ⅠR gene both including complete open reading frame of 465 bp and 4 518 bp,which encoded 154 and 1 505 amino acids respectively,and their protein molecular weight was17 011.71 Uand 169 267.26 U,isoelectric point was 9.36 and 6.70.The protein of IGF-Ⅰ had one signal peptide between site 49 and 50,while the protein of IGF-ⅠR had no signal peptide.The secondary structure of IGF-Ⅰgene coding product was mainly constituted ofα-helix and random coil,and it most probably（possibility of 62.5%）located in nucleus.However,the secondary structure of IGF ⅠR gene coding product was mainly constituted of random coil,and it most probably（possibility of 34.8%）located in cytoplasm.IGF-ⅠandIGF-ⅠR gene may act as hormone and signal sensor in biological processes,respectively.