Reporter genes

Biochemistry/MCB 568 -- Fall 2007
John W. Little--University of Arizona

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A reporter gene is one that codes for a product that is easy to measure. These genes are often used in situations in which the product of some gene of interest is difficult to assay quantitatively.

The most typical use of a reporter gene for our purposes is to analyze how a gene is regulated. Let's consider a typical gene as being composed of a regulatory region, lying upstream of the transcription start point, and a structural region, including the open reading frame and any 5' or 3' untranslated regions (UTR's):

The reporter gene would typically be attached to the regulatory region, using recombinant DNA methods, making an operon fusion like the second one shown above.

In this arrangement, anything that ordinarily affects the expression of the natural gene would also affect the expression of the reporter gene.

Reporter genes offer a big advantage, because one doesn't need a separate assay for each regulatory region being studied. Also, for many reporter genes simple indicator plate assays have been developed that allow one to determine levels of expression by the color of a bacterial or yeast colony, and perhaps to isolate mutants based on changes in the color. For instance, a bacterial strain making substantial amounts of beta-galactosidase will form a blue colony on a plate with X-gal; this allows one to identify cells with different levels of beta-galactosidase, and to use X-gal plates for any regulatory region driving expression of beta-galactosidase.

Typical reporter genes are: