Difference between revisions of "Part:BBa K1431101"

Revision as of 06:44, 17 October 2014

TetOn-3G, an ideal controller of mammalian gene expression with TRE-3G promoter+PolyA

Tet-On(Tetracycline-Controlled Transcriptional Activation,also known as rtTA2^S-M2) is a system of inducible gene expression systems for mammalian cells. Tet-On 3G (also known as rtTA-V16[citation needed]) is similar to Tet-On but was derived from rtTA2^S-S2 rather than rtTA2^S-M2. The Tet-On 3G protein has 5 amino acid differences compared to Tet-On which appear to increase its sensitivity to doxycycline(Dox) even further. Tet-On 3G is sensitive to 100-fold less Dox and is 7-fold more active than the original Tet-On.[http://en.wikipedia.org/wiki/Tetracycline-controlled_transcriptional_activation]

Target cells that express the Tet-On 3G transactivator protein and contain a gene of interest (GOI) under the control of a TRE3G promoter (P_TRE3G,BBa_K1431301[1]) will express high levels of GOI, but only when cultured in the presence of Dox, which is a synthetic tetracycline derivative(the mechanism of Tet-On 3G system show below). In the presence of Dox, Tet-On 3G binds specifically to PTRE3G and activates transcription of the downstream GOI. P_TRE3G lacks binding sites for endogenous mammalian transcription factors, so it is virtually silent in the absence of induction.

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The Dox concentrations required for induction of Tet-On Systems are far below cytotoxic levels for either cell culture or transgenic studies, and Tet-On 3G responds to even lower concentrations than its predecessors (Zhou et. al,. 2006). Note that Tet-On Systems respond well only to doxycycline, and not to tetracycline (Gossen & Bujard, 1995). The half-life of Dox in cell culture medium is 24 hours. To maintain continuous inducible GOI expression in cell culture, the medium should be replenished with Dox every 48 hours.(Source: Clontech)

Sequence and Features