绒山羊黑素皮质素受体4(MC4R)基因的克隆与序列分析

Cloning and sequence analysis on the melanocortin 4 receptor gene(MC4R) in Cashmere goat

绒山羊是绒肉兼用型动物,国内外对绒山羊绒用性能研究广泛,但对肉用性能研究相对较少。黑素皮质素受体4(melanocortin 4receptor,MC4R)主要分布在脑组织和肾上腺髓质及皮肤中,该基因突变会引起动物的体质量、能量稳态及采食量的改变。本研究采用PCR及RT-PCR等技术克隆得到了绒山羊MC4R基因的DNA及cD-NA片段,对比发现MC4R无内含子,长924bp,编码304个氨基酸,具有7个跨膜结构域。同源性比较显示:与绵羊、牛、马、猪、人、小鼠、兔、犬等同源性均高于85%,与绵羊同源性最高,达98%;与系统进化树分析结果一致。与其他哺乳动物相比,9处突变频率较高,分别位于93、152、160、162、165、182、213、221、230,且这些突变大多位于MC4R蛋白跨膜结构域及拓扑结构域,该研究对改良哺乳动物繁育性状提供了依据,对提高绒山羊肉用市场价值的研究发挥重要作用。但该突变是否与绒山羊特殊的毛肉用兼用性能有关,还有待进一步研究。

The melanocortin 4 receptor（MC4R） is a smallest member of the GPCR superfamily, mainly lying in the brain and adrenal medulla tissue. The its gene mutation can change the weight, energy homeostasis and appetite of animals. So in the study, a pair of specific primer was designed to amplify the cDNA sequence of MC4R using PCR and RT-PCR technique. The result showed that 924 bp cDNA sequence encoded 308AA, and there were 7 trans- membrane domains. Homology of nucleotide sequence and deduced amino acid were analyzed, the result showed that the homology were both higher than 85 % with ovis aries, bos grunniens, homo sapiens, s us scrofa,lupus familiaris, musMusculus, lutra lutra, macaca mulatta and ursus maritimus and so on,especially with ovis aries, the homology was up to 98~//00. But there were nine mutations, which were activing. These mutations were located in the trans- membrane domains. The research provides a theoretical basis to further study the gene function and a candidate gene of Cashmere goat＇s economic traits.