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N-Terminus pQE Vector Set

For high-level expression of N-terminally His-tagged proteins

  • pQE-30 vectors with MCS in all three reading frames for fast cloning
  • pQE-40 vector for poorly expressed proteins, short peptides
  • pQE-40 vector expresses DHFR-fusions, enhancing stability and antigenicity

This set provides 5 vectors (pQE-9, pQE-30, pQE-31, pQE-32, and pQE-40) for expression of N-terminally His-tagged proteins. pQE-30, pQE-31, and pQE-32 provide the multiple cloning site (MCS) in all three reading frames while pQE-9 has an alternative, shorter multiple cloning site. pQE-40 is designed for expression of DHFR-fusion proteins and is recommended for expression of poorly expressed proteins or short peptides, which are often prone to proteolysis, as DHFR enhances both stability and antigenicity. Since DHFR itself displays little immunogenicity in mouse and rat, DHFR-fusion proteins are ideal for epitope screening.

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Cat No./ID: 32915
N-Terminus pQE Vector Set
25 µg each: pQE-9, pQE-30, pQE-31, pQE-32, pQE-40
The N-Terminus pQE Vector Set is intended for molecular biology applications. This product is not intended for the diagnosis, prevention, or treatment of a disease.

Product Details

QIAexpress pQE vectors.

PT5: T5 promoter; lac O: lac operator; RBS: Ribosome-binding site; ATG: Start codon; 6xHis: 6xHis tag sequence; MCS: Multiple cloning site; Stop Codons: In all 3 reading frames; Col E1: Col E1 origin of replication; Ampicillin: Ampicillin resistance gene

pQE vectors.

QIAexpress pQE vectors combine a powerful phage T5 promoter, which is 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 (see figure QIAExpress pQE Vector). 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 figure pQE Vectors) enable placement of the His tag at either the N- or C-terminus of the recombinant protein.

Elements present in QIAexpress pQE vectors
Optimized promoter/operator element Consists of the phage T5 promoter and two lac operator sequences, which increase the probability of lac repressor binding and ensure efficient repression of the powerful T5 promoter
Synthetic ribosomal binding site RBSII For efficient translation
6xHis-tag coding sequence Either 5' or 3' to the polylinker cloning region
Translational stop codons In all reading frames for convenient preparation of expression constructs
Two strong transcriptional terminators t0 from phage lambda, and T1 from rrnB operon of E. coli, to prevent read-through transcription and ensure stability of the expression construct
ColE1 origin of replication From pBR322
Beta-lactamase gene (bla) Confers ampicillin resistance




Inserts encoding proteins of interest are cloned into appropriate constructs (For detailed information see the QIAexpressionist Handbook) 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
many applications, including:

  • Purification of functional, conformationally active proteins 
  • Purification under denaturing conditions for antibody production 
  • Crystallization for determination of three-dimensional structure
  • Assays involving protein–protein and protein–DNA interactions


All three reading frames provided Yes
Expression In vivo
Expression species E. coli
In-frame cloning necessary Yes
N- or C-terminal tag N-terminal tag
Tag 6xHis tag
Tag removal sequence No

Product Resources

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Kit Handbooks (1)
A handbook for high-level expression and purification of 6xHis-tagged proteins
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