Figure 1.

Viral expression system for mammalian cells. (A) An adenovirus-based system for tetracycline-controlled transcriptional activation of MscL expression which consists of co-infection of tetracycline transactivator (tTA) and MscL viruses. In the absence of tet, tTA binds to the tet-op promoter upstream of the MscL gene and induces expression. In the presence of tet, tTA is sequestered, inhibiting expression of MscL. (B) Western blot analysis of infected whole cells and (C) fluorescent images of immunostained His₆-tagged MscL in mammalian cells cultured at different concentration of tetracycline. Scale bar = 25 μm. (D) Western blot analysis of fractionated cells showing MscL subcellular localization. Note that a direct comparison of the levels of expression cannot be made because the strong Western blot bands of MscL in the nuclear membrane was due to more concentrated fraction compared to the plasma membrane fraction.