Vector: pIRES - (Jun/29/2006 )

A problem of a construct using a vector containing IRES seq.
The vector is pIRES-EGFP which can express Green fluorescence protein.
After substituting the EGFP sequence with Tdimer(a red fluorescence protein gene, ~1.4kb ), I can`t find any "red" cell after tansfeting (several times).

I have also tried to just insert Tdimer into pIRES6.1 which contains a MCS after IRES sequence.
However, it can still not expessed.

May there be some limits when utilizing IRES?

Thank U!

I had lots of problems with IRES before. I have read that a functional IRES may not work if the sequence following it is changed or modified . This is one of the reason I had to drop the idea of using the IRES.

Thank u for your reply!

It really made me confused!
IRES vectors from Clontech have a common feature that the selective sequence following IRES is no longer than 700bp. May the size of the following sequence be important?

Try to clone something within the 700bp size and look for expression.

Bcoz of the problem we had with IRES, I moved onto Bicistronic vectors (2 independent expression cassettes) and now sort of use them for most of my experiments. If the size is not a problem, u can try that with ur vectors.