细毛羊黑素皮质激素受体1(MC1R)基因与毛色表型的研究

为了研究黑素皮质激素受体1(MC1R)基因与黑色素生成的关系及该基因突变导致毛色发生改变的机理,研究采用RT-PCR和PCR等技术克隆得到了白色东北细毛羊MC1R基因长1 093 bp的cDNA片段,编码364个氨基酸,其中包括70个氨基酸信号肽和294个氨基酸的成熟肽,具有7个跨膜结构域。结果表明:细毛羊cDNA与绵羊、牛、马、人、小鼠、犬等同源性均大于91%,氨基酸序列与其他动物的同源性高于89%;除绵羊外与其他动物相比有5处发生突变,且这5处突变均位于MC1R蛋白跨膜结构区;而细毛羊和绵羊之间只有1处发生突变,由K→M,同源性达98.97%。说明细毛羊与绵羊的亲缘关系最近。

The study on the relationship between the melanocortin 1 receptor(MC1R) gene and the coat color phenotype in fine wool sheep

To study the relationship between the melanocortin 1 receptor gene(MC1R) and the formation of melanin,and to analyze the mechanism of the gene mutations causing the coat color changes in fine wool sheep,The 1 093 bp cDNA fragment of the MC1R gene from white Northeast fine-wool sheep was obtained from RT-PCR and PCR cloning,which encoded 364 amino acids that contained 70 amino-acid signal peptides and 294 amino-acid mature peptides with seven transmembrane domains.The results of homology comparison showed that the cDNA had a high degree of sequence homology,which was 91% great than that of sheep,cattle,horse,human,mouse and dog,and the homology of amino acid sequences was 89% higher than the other animals.Five amino acid mutations were detected compared with the other animals except sheep,which located at the transmembrane domains.Nevertheless,there was only one amino acid mutation from K → M between fine wool sheep and sheep,the homology between them was up to 98.97%,and the analysis of phylogenetic tree also confirmed the closest relationship between fine wool sheep and sheep.