中文摘要：

为构建中国地方品系荷包猪及莱芜黑猪SLA-3（命名为SLA-3-HB和SLA3-LW）原核表达载体及表达目的蛋白，试验通过PCR扩增获得SLA-3胞外区基因，并克隆至pMDl9TSimple载体，转化大肠杆菌Top10感受态细胞，酶切及测序筛选阳性重组质粒；重组质粒经酶切回收，目的片段进一步连接pET-21a（＋）表达载体，并转化大肠杆菌BL21感受态细胞，IPTG诱导目的基因的表达；SDS—PAGE检测目的蛋白。结果显示，PCR成功扩增SLA-3-HB及SLA-3-LW胞外区，大小约850bp，目的基因成功克隆至pMDl9-TSimple载体，并筛选序列正确的阳性重组质粒。进一步研究证实，SLA-3-HB及SLA-3LW成功连接到表达载体pET-21a（＋），插入片段长度均为831bp。经诱导后，SLA-3HB及SLA-3-LW均成功表达，表达蛋白大小为31ku，相对表达含量达到40％。本研究成功构建了中国地方品系荷包猪及莱芜黑猪SLA-3原核表达载体，为进一步研究其结构和功能奠定基础。

英文摘要：

To construct the prokaryotic expressing vector of SLA-3 derived from Hebao and Laiwu pigs （named as SLA-3-HB and SLA-3-LW） and to express the interest of protein,the extracellu- lar domain of SLA-3 were amplified by PCR,and then they were cloned into the pMD19-T Simple vector followed by transforming into Escherichia coli Topl0. By cleavage and sequencing, the pos- itive clones were selected. After cleavage and purification of the recombinant plasmids,the interest of genes were further ligated to pET-21a（q-） and transformed into the Escherichia coli BL21. The interest of genes were induced to express by IPTG and the interest of proteins were detected by SDS-PAGE. The results showed that the extracellular domain of SLA-a-HB and SLA-3-LW were successfully amplified with the molecular weight of 850 bp. It was also shown that the SLA- 3-HB and SLA-3-LW were successfully cloned into pMD19-T Simple vector and the positive re- combinant plasmids with correct sequences were selected. Further study proved that SLA-3-HB and SLA-3-LW were successfully ligated into pET-21a（-k） with the 831 bp inserted fragments. After induction, SLA-3-HB and SLA-a-LW were all expressed successfully and the molecular weight of the interest of proteins were about 31 ku,and the contents of the expression of the proteins reached 40 percent. In this study, the prokaryotic expression vector of SLA-3 gene derived from Hebao and Laiwu pigs,which would lay a base for furter study the structure and function of the interest of proteins.