GFP or LacZ for quantification of promoter activity? - (Mar/03/2006 )

anyone has idea that whether we will have problems when we use gfp quanitification of promoter activity instread of using lacZ, I mean for a publication

I am not sure what you mean. There are different GFPs, stable and unstable ones. The unstable one I used had a half life of 30 minutes, so it would degrade in the cell. It was more accurate than lacZ or stable GFP because you would be able to see multiple upregulation events over the growth cycle. LacZ and stable GFP don't degrade, so they collect in the cell. One problem with the unstable gfp is that if your promoter is not strong, you may not see any expression. I think it depends what you are looking for. If you just want to see expression of a gene then both lacZ and gfp (stable and unstable) are good. But if you want to expression of the gene in a biofilm for example, then gfp is better because you can see where in the biofilm its being expressed...which cells are expressing and so on. TO answer you question, people have used gfp to quantify promoter activity and it has been published so I don't see a problem with you using gfp.

In fact, I am using gfpmut3 to transcriptionally fuse with promoter. just wonder why less work did that, instead, frequently, lacZ was used

well lacZ has been around a lot longer and so the tools for fusing promoters to lacZ are much more readily available. Also, you nede a machine that can measure gfp fluorescence (excite it at the correct wavelength and pick up the emitted florescence) whereas, lacZ can be measured using a subtrate and a spectrophotometer.

If you have the equipment for measuring GFP signal and there aren't any issues with stability/genetic manipulation, I would use GFP for publication.

It is much more versatile and allows you to localize expression in the cell through confocal microscopy.

-Matt