GeneSwitch™ Mammalian Expression Kit, complete kit

Sorry, all GeneSwitch cell lines have been discontinued.

The GeneSwitch protein contains functional domains from different transcription factors, allowing it to function as a ligand-dependent transcription factor to activate expression of both the gene of interest and its own gene. The GeneSwitch protein exhibits the following characteristics:

- Since the GAL4 DBD is derived from a yeast protein, the GeneSwitch protein has no effect on endogenous genes and can only activate transcription of genes whose expression is controlled by a GAL4 UAS (i.e., the gene of interest and the regulatory fusion gene).
- The GAL4 DBD binds to an individual 17-nucleotide GAL4-binding site as a homodimer. The pGene/V5-His and pSwitch plasmids contain 6 and 4 copies of the GAL4 binding site, respectively, although it is not known if all of the GAL4-binding sites are occupied at any given time.
- The truncated hPR-LBD contains a 19 amino acid deletion from its C-terminal end that abolishes its ability to bind to progesterone, other endogenous steroid hormones, or other progesterone agonists, but still enables it to bind with high affinity to mifepristone.
- The p65 AD is a strong transcriptional activator but is derived from a human protein, to minimize possible toxic or pleiotropic effects associated with viral transactivation domains.

When a co-transfection is performed, there is no way of testing the double stable cell line for functional TetR or GeneSwitch protein, respectively. On the other hand, when sequential transfection is performed, one can functionally test the generated T-REx or GeneSwitch cell line by transiently transfecting the lacZ expression control plasmid and then picking a clone that shows the lowest basal level of expression of lacZ in the absence of the inducer, and the highest level of lacZ in the presence of the inducer. This clone can then be expanded and used to transfect the T-REx or GeneSwitch expression construct, as the case may be.

With the GeneSwitch system, it is possible to have the absolute lowest basal levels of expression of the gene of interest, whereas the T-REx system may be a little leaky due to the inevitable presence of tetracycline in FBS. The induced level of expression in the GeneSwitch system can be even higher than that seen with the CMV promoter. The disadvantage of the GeneSwitch system is that the expression does not appear to switch off very easily in culture, although it has been demonstrated to function beautifully in transgenics. The T-REx system, on the other hand, can be switched on and off by the addition and removal of the inducer.

We offer three unique mammalian expression systems for inducible/regulated expression of the gene of interest:

- T-REx system
- Flp-In T-REx system
- GeneSwitch system

Please see below to see how they compare with one another:
System -- Basal Expression Level -- Induced Expression Level -- Response time to Maximal Expression -- Transgenic Appliation
T-Rex system -- Low -- Highest -- High -- Suitable
Flp-In T-REx system -- Lower -- High -- 24-48 hrs -- Suitable
GeneSwitch system -- Lowest -- High -- 24-48 hrs -- Suitable