Assays for Transcriptional Activity Based on the Luciferase Reporter Gene

Reporter genes provide easy and efficient methods for the indirect measurement of relative rates of transcription. Utilizing common DNA cloning methods, a putative regulatory region can be coupled to the coding sequence of a reporter gene such that expression of the reporter protein product varies according to the regulatory potential of the DNA tested. The assays for reporter enzymes have the advantage of high sensitivity with low background, and, although an indirect measure, the amount of protein product is usually directly proportional to the level of transcriptional activation. Alternatives to reporter gene assays such as the direct measurement of the level of specific mRNAs for the endogenous gene can be influenced by RNA stability changes as well as transcription rates in response to stimulation. Assays for mRNA are also more labor intensive and difficult to quantify.