Bicistronic Vectors

Victor Levenson levenson at
Wed May 28 18:39:36 EST 1997

Your.Name at Mail.Server.CSIRO.AU (Your Name) wrote:


>Has anyone had any experience with the new bicistronic vectors for mammalian 
>expression (ie: selection pressure placed on both neoR and gene of interest as 
>they are driven off the same promoter such that neo resistant clones should 
>also express gene of interest). I am particularly interested in the pIRES1neo 
>(CLONTECH) for generating stable transfectants. Are they as good as they 
>sound? Is it possible to get neoR clones that do not express your gene of 
>interest (thru some weird recombination event etc)? 

>Thanks muchly;


>David.Tucker at


I have just finished playing with IRES vectors (made a family with
Pac, Hygro, HisD and Bleo from the initial pCIN4 - Biotechniques,
1996, v.20, #1, p102: S.Rees et al) and the bottom line is: it all
depends on the gene that is upstream of IRES. In my case the marker
was  b-gal and I got beautiful mosaic colonies (partially blue,
partially not), resistant to selection agent. I thought about
alternative splicing and - sure enough, it turned out that b-gal gene
contains a host of splice signals. Now I am checking whether GFP
cloned into the same vectros will give a better result. If you are
interested drop me a note and I will e-mail you the "verdict".


Victor Levenson MD/PhD
Res Asst Prof
UIC, Dept of Genetics M/C 669
900 S Ashland Ave
Chicago IL 60607
levenson at 

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