why these guys use T7 instead of CMV? - for transfection (May/24/2011 )

I am reading a paper by Nakaya et al., 2001. In figure 1 they show cloning of the whole virus genome into a plasmid (must be pBR322) that has T7 promoter. and they transfect into HEp-2 cells. I have personally never used T7 promoter for transfection into Eukaryotic cells. We learned we must use CMV.

Click here to see the paper

T7 is most commonly used to produce RNA via the a RNA polymerase for making probes for northerns and ISH, as opposed to the CMV promoter which is a viral promoter used for many eukarotic expression systems.

In theory you can use any promoter to produce RNA which will then be translated; it all depends on how much protein you want to be produced. If you want lots of protein use a plasmid with CMV or SV40 or other viral promoter as these are typically very high expression as a virus requires lots of protein in a short time. for lower expression you can use mammalian or insect promoters.

Amen,

Bob1, I can't recall how many times you've come to rescue me in the past 4 years, thank you so much.