牦牛MC4R基因及其蛋白结构预测分析

Nucleotide and Predicted Protein Structure Analysis of MC4R Gene of Yak

根据普通牛MC4R基因序列设计同源引物,扩增克隆牦牛MC4R基因,对牦牛与普通牛MC4R基因及其蛋白结构进行生物信息学分析。与普通牛MC4R基因相比,牦牛在该基因存在5个多态位点,其中3个在密码子第3位,2个位点在密码子第1位;4个牦牛个体中有1个与其他个体存在2个变异位点且在密码子第3位;牦牛与普通牛在MC4R蛋白2个氨基酸的差异只引起两物种MC4R蛋白二级结构组分的细微差异。MC4R蛋白在牦牛和普通牛之间保守性较强,MC4R基因可能在哺乳类数百万年的进化历程中受到较强的进化抑制或净化进化。为研究MC4R基因在牦牛食欲控制、体重调节、脂肪沉积和能量平衡调节等方面提供基础资料。

This work was aimed to clone the MC4R gene of yak （Bos grunniens） and analyze its structure and predict the protein structure. Results of this work were expected to provide basic data for further study of the roles of MC4R gene on body weight controlling, restricted feeding weight, fat deposition and energy balance of yak. Homologous primers were designed based on bovine MC4R gene to clone yak MC4R gene. Bioinformatics analysis was conducted to detect the variation of yak MC4R gene and predict the protein structures. Compared with the MC4R gene of bovine, five polymorphic sites was detected in yaks and three were located at the third nucleotide of the genetic code and two at the first. Among the four yak individuals, only two polymorphic sites were detected at the third nueleotide of the genetic code. We predicted that the two amino acid substitutions might lead to slight changes in the secondary structure of MC4R, and the protein structure of MC4R was highly homologous between yak and cattle, suggesting that MC4R gene might have been subjected to substantial constraints or strong purifying selection during the several million years of evolution.