For parallel expression of His-tagged proteins in E. coli, mammalian cells, and baculovirus-infected insect cells using a single construct
The pQE TriSystem Vector allows for high-level expression of His-tagged proteins from a single vector containing three different expression systems. There is the T5 promoter/lac operator transcription–translation system for expression in E. coli, the p10 promoter for baculovirus-based expression in insect cells, and the CAG (CMV/actin/globin) promoter for expression in mammalian cells.
The pQE-TriSystem vector contains CAG, T5, and p10 promoters that enable 6xHis-tagged protein expression in mammalian, E. coli, and baculovirus-infected insect cells, respectively (see figure pQE TriSystem). Preliminary studies can be carried out in bacterial expression systems, using the strong T5 promoter, which is recognized by E. coli polymerase, and allows efficient expression of proteins in any E. coli strain. If expression in mammalian or insect cells is required — to obtain post-translational modifications, for example — the same construct can be used without the need for time-consuming subcloning procedures.
QIAexpress pQE vectors combine a powerful phage T5 promoter (recognized by E. coli RNA polymerase) with a double lac operator repression module to provide tightly regulated, high-level expression of recombinant proteins in E. coli. Protein synthesis is effectively blocked in the presence of high levels of lac repressor and the stability of cytotoxic constructs is enhanced. The pQE vectors (see table and figure pQE Vectors) enable placement of the 6xHis tag at either the N- or C-terminus of the recombinant protein.
Inserts encoding proteins of interest are cloned into appropriate constructs and transformed into a suitable E. coli strain for expression. Expression is induced by addition of IPTG. Vector pQE-TriSystem constructs can be transformed into E. coli, used as a shuttle vector for recombinant protein expression in insect cells, or transfected into mammalian cells.
The QIAexpress Expression System provides high-level expression of proteins suitable for
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