Rosetta 系列的表达菌株可以提供T7 RNA 聚合酶，它能表达PET 系列载体上的外源基因。。。pGEX 系列载体上的外源基因不需要 T7 RNA 聚合酶，普通的大肠杆菌经 IPTG 诱导即可表达 Tac 启动子是一组由 Lac 和 trp 启动子人工构建的杂合启动子，受 Lac 阻遏蛋白的负调节，它的启动能力比 Lac 和 trp 都强。其中 Tac 1 是由 Trp 启动子的－35 区加上一个合成的46 bp DNA 片段(包括 Pribnow 盒)和 Lac 操纵基因构成，Tac 12 是由 Trp 的启动子-35 区和 Lac启动子的-10 区，加上Lac 操纵子中的操纵基因部分和 SD 序列融合而成 蛋白标签： A myc tag is a polypeptide protein tag derived from the c-myc gene product that can be added to a protein using recombinant DNA technology. It can be used for affinity chromatography, then used to separate recombinant, overexpressed protein from wild type protein expressed by the host organism. It can also be used in the isolation of protein complexes with multiple subunits. A myc tag can be used in many different assays that require recognition by an antibody. If there is no antibody against the studied protein, adding a myc-tag allows one to follow the protein with an antibody against the Myc epitope. Examples are cellular localization studies by immunofluorescence or detection by Western blotting. The peptide sequence of the myc-tag is (in 1- and 3-letter codes, respectively): N-EQKLISEEDL-C, N-Glu-Gln-Lys-Leu-Ile-Ser-Glu-Glu-Asp-Leu-C, where N stands for Amino-terminus and C stands for Carboxy terminus. The tag is approximately 1202 Daltons in atomic mass and has 10 amino acids. It can be fused to the C-terminus and the N-terminus of a protein. It is advisable not to fuse the tag directly behind the signal peptide of a secretory protein, since it can interfere with translocation into the secretory pathway. A monoclonal antibody against...
