中文摘要：

采用RT-PCR方法扩增并克隆麦洼牦牛G蛋白信号转导调节因子5（regulator of G protein signaling 5,RGS5）基因序列,利用ClustalX 1.83和Mega 5.0软件构建系统进化树,并选用多种生物信息学软件进行序列分析和蛋白结构预测。结果表明,所得麦洼牦牛RGS5基因长度为863bp,包含1个546bp的完整开放阅读框,编码181个氨基酸,GenBank登录号为KJ867514。系统进化树分析发现,麦洼牦牛RGS5氨基酸序列与普通牛亲缘关系最近,其次是山羊和绵羊。RGS5基因编码的蛋白质分子质量为20.94ku,理论等电点（PI）为6.35,它是一种以α-螺旋为主,不含信号肽的非跨膜、不稳定性蛋白。三级结构预测显示,麦洼牦牛与人RGS5蛋白三级结构相似性高达90.51%。以上结果为深入研究RGS蛋白功能积累科学资料。

英文摘要：

Regulator of G protein signaling 5was cloned and analyzed by RT-PCR and bioinformatic methods.Phylogenetic tree was constructed using ClustalX 1.83 and Mega 5.0.The results showed that the sequence of RGS5 was 863bp and contained an open reading frame of 546 bp,which encoded 181 amino acids.Phylogenetic tree indicated that amino acids of RGS5 in Maiwa yak had high homology with cattle.The molecular mass of RGS5 protein was 20.94 ku and the theoretical PI was 6.35.The RGS5 was an unstable protein.It mainly contained helix with no signal peptide and transmembrane domain.Tertiary structure of RGS5 protein of Maiwa yak had similar tertiary structure with human RGS5 protein.It would be benefit for further study on function of RGS in Maiwa yak.