Gentarget's inducible lentiviral expression vectors contains a strong constitutive promoter (CMV or H1) that integrated with two copies of TetR binding sequences. This modification does not change promoter's constitutive expression nature. The GOI (gene of interest) can be expressed in high level as regular promoter without any induction. However, optionally, the lentivectors can be used as tetracycline inducible expression. To achieve this inducible expression, the TetR protein has to be present in advance to bind the promoter, blocking the expression. And the expression is induced after addition of tetracycline which removes the TetR from the promoter.  Please see Inducible lentiviral system page for more information.

The presence of TetR can be achieved by the following methods:

1. use expression TetR stable cell lines that constantly express tetR protein;
2. Co-transfect a tetR expression plasmid with target inducible expression vector;
3. Co-transduce the tetR lentiviral particles and the inducible gene expression lentiviral particles into your cell of interest;

The premade TetR lentiviral particle is the best method to delivery the TetR protein. Gentarget provides TetR expression lentiviral particles with different antibiotic markers. Each particle can be used as follows:

1. It can be transduced alone into any host cells of your interest to generate TetR expression stable cell line. The generated stable cell is then transduced with any inducible target expression particles, and the double transduced cells will demonstrate a tetracycline dose-dependent inducible expression of the target.
2. It can be co-transduced with any inducible target expression lentiviral particles. And the double transduced cells (selected via double antibiotic markers) will demonstrate a tetracycline dose-dependent inducible expression of the target.

What's the difference between Gentarget's inducible system and other regulated expression?

Gentarget's inducible lentivectors (shRNA vectors and expression vectors) have TetR binding sequences inserted into its constitutive promoter (H1 or CMV). This modification does not change promoter's constitutive expression property. It becomes inducible system only when TetR protein is present to block the expression. And addition of tetracycline will remove TetR from promoter to induce the expression. So it is an optional inducible system.

Comparatively, the other tetracycline inducible expression system has a silent promoter with modification for binding to a transcriptional activator.  Their expression will only be turned on after a transcriptional activator binds to the promoters. The transcriptional activator binding to promoters is dependent upon the presence of tetracycline (or Dox) (so called: Tet-on system) or absence of tetracycline (so called: Tet-off system).  So it needs the transcriptional activator (tTA or rtTA) along with Tetracycline (or Dox) for the inducible expression. But They (Tet-on and Tet-off) can not be used alone as a constitutive expression.

Please see each product's manual below: