中文摘要：

本研究以β2-肾上腺素能受体（β2-adrenergic receptor,β2-AR）基因的保守序列设计了1对PCR引物,通过PCR技术首次获得了萨福克、小尾寒羊和中国美利奴（新疆型）3个绵羊（Ovisaries）品种的β2-AR基因（GenBank登录号分别为EU707939、EU707940和EU707941）,该基因含一个1257bp的开放阅读框（ORF）,编码418个氨基酸残基。核苷酸序列分析显示,绵羊β2-AR基因与牛、猪、大鼠和人的相似性分别为98.4%、88.5%、84.2%和80.5%。通过基因合成技术合成了双拷贝的绵羊β2-AR第二细胞外环编码区DNA,并将其与pET32C（＋）重组。重组菌以1mmol/L IPTG诱导,通过SDS-PAGE和Western blot分析,绵羊β2-AR第二细胞外环融合蛋白在大肠杆菌（Escherichia coli）BL21（DE3）中成功表达,表达产物分子量约为26kD,表达水平最高占菌体总蛋白的40.3%。

英文摘要：

The β2-adrenergic receptor（β2-AR） genes of three breeds of sheep（Ovis aries） were cloned forthe first time from Suffolk,Small Tail Han and Chinese Merino（Xinjiang type） with a pair of PCR primer corresponding to the consensus sequence of mammalian β2-AR（GenBank accession No.EU707939,EU707940 and EU707941）.The nucleotide sequence data showed that the coding region of the gene consisted of 1257 bp open reading frame which encoded 418 amino acid residues.The sheep β2-AR coding region nucleotide sequence was 98.4%,88.5%,84.2%and 80.5%identical to those of bovine,porcine,rat and human,respectively.Two copies of the nucleotide sequence coding for the second extracellular loop of sheep β2-AR were synthesized and then cloned into pET-32C（＋） expression vector.Afterbeing transformed into Escherichia coli BL21（DE3） and induced by 1 mmol/L IPTG,the recombinant fusion protein expressed in cytoplasm.SDS-PAGE and Western blotting results revealed that the molecular weight of the protein was about 26 kD,and the expression level was 40.3% of total bacterial protein.