Plasmid-Based Reporter Genes: Assays for -Galactosidase and Alkaline Phosphatase Activities

Reporter genes encode easily measurable traits. Most commonly, they are used to investigate the expression of other genes for which functional assays are not available or for which measurement of expressed product is difficult. This is often done through constructing a genetic fusion in which expression of the target gene also drives expression of the reporter gene product. Measurement of reporter gene product gives a direct readout for expression of the target gene (1 ). Even with the advent of technologies such as DNA microarrays, reporter genes continue to provide a powerful tool for studying gene expression (2 –4 ).