Before the Tet-One Systems were developed, Clontech’s Tet-On and Tet-Off products all required two separate vectors: one to introduce the doxycycline-responsive transactivator protein into your target cells, and the other to introduce the inducible promoter controlling your gene of interest.
The Tet-One Systems provide both of these components on a single vector. The Tet-On 3G transactivator is expressed in the forward direction from the human phosphoglycerate kinase 1 promoter, and the cloned gene of interest is expressed from the PTRE3GS promoter in the reverse orientation. Compared to the two-vector Tet-On 3G Systems, all previously published all-in-one vectors have shown a low signal-to-noise ratio, typically providing only 50–100-fold induced expression, even in selected clones. Clontech’s Tet-One Systems are based on an all-in-one design that has shown up to 25,000-fold induction (Heinz et al, 2011).