细毛羊黑素皮质激素受体1(MC1R)基因与毛色表型的研究

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

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。

To study the relationship between the melanocortin 1 receptor gene （MC1 R） and the formation of melanin, and to analyze the mecha nism of the gene mutations causing the coat color changes in fine wool sheep, The 1 093 bp cDNA fragment of the MC 1R gene from white North- east 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.