Lac Switch

Martin Kennedy mkennedy at
Tue Dec 7 21:36:47 EST 1993

In article <1993Dec6.213759.24631 at>, bernard at (Bernard Murray) writes:
> In article <CHMFnw.1uz at>, jgraham at (the End) writes:
>> In <1993Dec5.205157.162 at> vaughan at writes:
>> >Has anyone had a positive experience with the Lac-Switch system
>> >sold by Stratagene? I am scaling up to try it, but have been
>> >burned before.Any comments welcome (relative to Lac Switch that is)
> Stratagene Catalogue 1993 - New Product -page 43
> LacSwitch Inducible Mammalian Expression System
> Basically it seems to use LacI to repress transcription and this can be
> released by treatment with IPTG (this all happening in mammalian cells).
> This system had me intrigued as well and I was hoping someone would take
> the plunge and let us know how it performs.  Does anyone know of any
> equivalent system (commercial or non-commercial)?
> Bernard Murray, Ph.D.

Sounds very much like something described by Baim et al (1991) PNAS 88,
5072-5076:  A chimeric mammalian transactivator based on the lac repressor that
is regulated by temperature and IPTG. 

Uses a minimal SV40 promoter linked to lac operator sequences, and a lacI
activator protein containing the transcriptional activator domain of HSV VP16. 
The chimeric lacI protein (LAP267) is heat sensitive at 39.5 degrees, but its 
activity can be rescued by addition of IPTG.  They report 1200 fold increases
in CAT activity 24hours after adding IPTG in this system.

I've never used it, and I'm not sure I really understand it - I just happended
to have a copy of the paper ;-}

be rescued 



NNNN   NN  Martin A Kennedy (E-mail = mkennedy at  ZZZZZZZ  
NN NN  NN       Cytogenetic and Molecular Oncology Unit          ZZZ
NN  NN NN           Christchurch School of Medicine            ZZZ
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