Inducible euk. expression vectors

Nigel Kenward mbxnjk at
Wed Aug 16 02:51:14 EST 1995

moffat at (John Moffat) wrote:
>I need information about inducible expression vectors for stable transfection
>of a human epithelial cell line. Not keen on exposing cells to dexamethasone
>or heavy metals. How good are tet-repressor based sytems and are any available
>commercially? What about vectors using the lac repressor? Any others available?
>any comments opinions pointers most appreciated.
>John Moffat Biochem Dept Wash U. Schoolf of Medicine St Louis
>moffat at

Hi John,
I'm talking independantly and theoretically here, but I know Stratagene have a system called LacSwitch which basically works as follows:
You transfect 2 plasmids into your cells (each has a different antibiotic selection). It basically puts your sequence of interest under the control of the Lac repressor. In normal conditions the gene is sswitched off by the action of the second plasmid, but on addition of tiny amounts of IPTG, the repressor is switched off and your plasmid gets going using normal viral promoters to do the biz.
This is a VERY simplified (and quite possibly a little inaccurate) description as I haven't looked into it for a year or two. I know the Stratagene guys love it, and are amazed it hasn't taken off so far - maybe you're the guy to put it in the forefront of molecular biology !
Anyway, hope you can get some info. on it.
All the best,

Nigel Kenward              TEL:+44 (0)115 9249924 ex. 44789
Dept. of Biochemistry      FAX:+44 (0)115 9422225
Queens Medical Centre      Email:mbxnjk at
Clifton Boulevard          URL:

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