TetR (tetracycline regulator) for Inducible Expression:

TetR (tetracycline regulator) (click to see its codon sequence), is the key regulatory protein in the tetracycline-controlled inducible gene expression system.  When TetR protein is present it binds to the promoter, blocking expression. Induction of expression is accomplished by addition of tetracycline (or doxycycline) which removes TetR from the promoter.  In Tet-OFF system, it binds to promoter without Tetracycline (or Dox),  which activates the expression until Dox is absent which turn off the expression.

TetR Expression Lentivirus:

GenTarget provides optional inducible expression lentivirus in which the target or shRNA is driven by a modified CMV or H1 promoter. Those promoters have integrated with two copies of the TetR binding sequences. This modification does not change the promoter’s constitutive expression. Therefore, the target or shRNA can be expressed at a high level without induction, or by tetracycline induced expression, so called Optional inducible expression. 

So, when TetR present, you can turn those expression as inducible expression. GenTarget’s provides TetR expression lentivirus with a variety of antibiotic markers. TetR is expressed under either a super strong CMV promoter (producing the highest TetR protein level) or an enhanced EF1α promoter (a tissue nonspecific strong promoter with no silencing effects during long-term culture).

See the TetR expression vector map scheme below.

Q: What is the difference between GenTarget’s inducible system and other inducible expression systems? 

A: The GenTarget system is an optional inducible system. 

GenTarget’s inducible lentivectors (shRNA vectors and expression vectors) have TetR binding sequences inserted into their constitutive promoter (H1 or CMV). This modification does not change the promoter’s constitutive expression property. The system becomes inducible only when the TetR protein is present to block expression. Addition of tetracycline removes TetR from the promoter, inducing expression.  

By comparison, other tetracycline-inducible expression systems use a silent promoter that has been modified to bind to a TetR.  Expression is turned on only when the TetR binds to the promoter  and turn off by Dox (Tet-OFF). The Tet-On and Tet-Off systems require a transcriptional activator (tTA or rtTA) along with tetracycline or Dox for inducible expression, but the Tet-on and Tet-off vector cannot be used alone for constitutive expression. 

Please see  Product’s Manual .