Reporter genes are generally joined to a regulatory DNA sequence in an expression vector that is usually propagated in Escherichia coli before transfection into the cell type of interest.1 A control reporter driven by a strong, constitutive promoter is cotransfected with the experimental reporter plasmid to normalize for transfection efficiency and to account for the fact that expression of the experimental reporter may vary in different cell types. After allowing time for gene expression, the cells are assayed for reporter mRNA, the reporter protein itself, or for the activity of the reporter protein. Detection of the reporter gene product usually requires cell lysis, although some products are amenable to in situ analysis.
Ideally, a reporter gene encodes for a protein whose activity can be detected with high sensitivity above any endogenous activity and that displays a wide dynamic range of response (over several orders of magnitude). The assay should be ...
