For regulated high-level expression with pQE Vectors
  • Cells contain pREP4 plasmid encoding lac repressor
  • Lac repressor in trans ensures tightly-regulated expression
Cells in ther two E. coli Host Strains M15[pREP4] and SG13009[pREP4] carry the repressor plasmid pREP4, which constitutively expresses lac repressor at high levels, enabling trans repression of protein expression prior to IPTG induction. The pREP4 plasmid is maintained by kanamycin selection.
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Please note: 34210: E. coli Host Strains has been discontinued as of December 31, 2013. For more information, please contact QIAGEN Technical Services.
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E. coli Host Strains
One stab culture each: E. coli M15[pREP4], SG13009[pREP4]

E. coli Host Strains are intended for molecular biology applications. These products are not intended for the diagnosis, prevention, or treatment of a disease.

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The repressor plasmid pREP4 constitutively expresses the in trans lac repressor at high levels. This results in repression of expression of the recombinant protein from the pQE vector that has lac operators in the promoter region to which the lac repressor binds, hence, ensuring tightly-regulated expression. Added IPTG binds to the lac repressor protein, inactivating it, allowing expression of the recombinant protein. The pREP4 plasmid is maintained by kanamycin selection. The SG13009[pREP4] strain may be useful for the production of proteins that are poorly expressed in M15[pREP4].

E .coli host strains are highly suited for the regulated expression of: 

  • 6-His-tagged proteins
  • 6-His-tagged DHFR-fusion proteins

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Kit Handbooks
A handbook for high-level expression and purification of 6xHis-tagged proteins
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