pBAD/His和PBAD/Myc-His載體質粒是衍生于pBR322載體。載體設計用來在大腸桿菌中進行可調節，劑量依賴性的表達和純化重組目的蛋 白。使用大腸桿菌araBAD啟動子（pBAD）增強了大腸桿菌重組蛋白可溶性表達的水平。pBAD/His和pBAD/Myc His載體上的調節蛋白AraC能夠調控pBad啟動子。

pBAD/Myc-His A,B,C 載體簡介 The pBAD/His and pBAD/Myc-His plasmids are pBR322-derived expression vectors designed for regulated, dose-dependent recombinant protein expression and purification in E. coli. Optimum levels of soluble, recombinant protein are possible using the araBAD promoter (PBAD) from E. coli. The regulatory protein, AraC, is provided on the pBAD/His and pBAD/Myc-His vectors allowing regulation of PBAD.

The pBAD/Myc-His Kit provides all of the necessary reagents to express your protein in a tightly regulated fashion. The pBAD/Myc-His vector expresses native proteins or fusion proteins with a C-terminal tag. The vector provides:
 The araBAD promoter for tightly regulated expression
 Translation initiation signals optimized for E. coliexpression
 C-terminal polyhistidine (6xHis) tag for purification with nickel-chelating resin or detection with an Anti-His(C-term) Antibody
 C-terminal c-myc epitope for detection and analysis with an Anti-myc Antibody
Three vectors are provided (A, B, and C). Each has the C-terminal tag in a different reading frame relative to the multiple cloning site to simplify in-frame cloning of your gene. L-阿拉伯糖調控表達 In the presence of L-arabinose, expression from PBAD is turned on while the absence of L-arabinose produces very low levels of transcription from PBAD (Lee, 1980; Lee et al., 1987). Uninduced levels are repressed even further by growth in the presence of glucose. Glucose reduces the levels of 3′,5′-cyclic AMP, thus lowering expression of the catabolite-repressed PBAD promoter (Miyada et al., 1984). By varying the concentration of L-arabinose, protein expression levels can be optimized to ensure maximum expression of soluble protein. In addition, the tight regulation of PBAD by AraC is useful for expression of potentially toxic or essential genes (Carson et al., 1991; Dalbey and Wickner, 1985; Guzman et al., 1992; Kuhn and Wickner, 1985; Russell et al., 1989; San Millan et al., 1989). For more information on the mechanism of expression and repression of the ara regulon, refer to Schleif, 1992.