Cloning & Expression

T7 Promoter System

T7 Vectors for Highest Expression Levels in Bacteria

  • FLAG® vectors for highly sensitive detection and purification using ANTI-FLAG® antibodies, resins, and plates
  • MAT™ vectors for high quality purification using HIS-Select™ resins and 96-well plates
  • N- or C- terminal fusions
  • Dual tag configurations
  • Cytoplasmic expression
  • lac operator to reduce "leaky" expression
  • Enterokinase removal of N-terminal FLAG tags

Vector Selection Guide

Bacterial Expression Vectors
T7 Promotor System
  Tag Location Tag ab resistance Product No. Description
Single Tag N-Terminal FLAG ampr/kanr P9616 pT7 FLAG 3
amp P1118 pT7 FLAG 1
MAT β-lactamase (ampr) E5780 pT7 MAT 1
C-Terminal FLAG ampr/kanr P9743 pT7 FLAG 4
amp P1243 pT7 FLAG 2
MAT β-lactamase (ampr) E5655 pT7 MAT 2
Dual Tag N,C-Terminal FLAG and MAT E5280 pT7 FLAG-MAT 1
E4905 pT7 MAT-FLAG 2
N-Terminal E5155 pT7 MAT-FLAG 1
C-Terminal E5030 pT7 FLAG-MAT 2


Product MCS Region
P1118, pT7-FLAG™-1
N-terminal Met-FLAG

P1243, pT7-FLAG™-2
C-terminal FLAG

E5780, pT7-MAT™-1
N-terminal MAT
E5655, pT7-MAT™-2
C-terminal MAT
E5280, pT7-FLAG-MAT™-1
N-terminal Met-FLAG, C-terminal MAT (dual tag)

E4905, pT7-MAT™-FLAG-2
N-terminal MAT,C-terminal FLAG (dual tag)
E5155, pT7-MAT-FLAG™-1
N-terminal MAT-FLAG (dual tag)

E5030, pT7-FLAG-MAT™-2
C-terminal FLAG-MAT (dual tag)

back to top

  • Kanamycin gene and ampicillin gene for greater selection flexibility in E. coli


Product MCS Region
P9618, pT7-FLAG™-3
N-terminal Met-FLAG

P9743, pT7-FLAG™-4
C-terminal FLAG

T7 Vector Features
Bacterial T7 promoter-based vectors allow for expression, detection and purification of recombinant FLAG and MAT (Metal Affinity Tag) fusions in E. coli. Several vectors containing the T7 promoter offer dual tag options for FLAG and MAT-tagged fusion proteins. These vectors confer ampicillin resistance for easy selection of positive transformants. Additionally, the vectors contain the T1T2 transcriptional terminator, the pMB1 (derivative of pBR322) origin of replication, the f1 origin and the lacI gene for repression of the T7 promoter.

pT7-FLAG™ and pT7-MAT™ vectors offer the very strong T7/lac promoter. These expression vectors produce even higher yields of recombinant protein than the tac promoter system. However, the T7 promoter is known for background ("leaky") expression, which can be a drawback when recombinant proteins are toxic to the host cell. Therefore, our vectors contain the lac operator (lacO) sequences immediately downstream from the promoter to reduce leaky expression. Unlike the tac promoter system, pT7 vectors must be expressed in hosts containing a source of the T7 polymerase such as (DE3) lysogenic strains.

The MAT tag or Metal Affinity Tag (HNHRHKH) has been created for purification of recombinant MAT fusion proteins using HIS-Select Nickel and Cobalt Affinity Gels. HIS-Select products allow for highly selective purification of histidine-tagged fusion proteins such as MAT fusions. Many of our newest vectors make use of the MAT tag, often in combination with the well-known FLAG tag. MAT tag containing vectors are offered in formats for N-terminal or C-terminal tagging.

Enterokinase Removal of FLAG Tags
The recognition sequence for enterokinase, Asp-Asp-Asp-Asp-Lys, is found at the C-terminal end of the FLAG epitope tag. Removal of FLAG is possible in all fusion proteins containing an N-terminal FLAG sequence. Dual tag fusion proteins may also be cleaved with enterokinase for removal of one or more tags, depending on the position of FLAG in the protein sequence.

back to top
back to Expression Vectors