Study of transcriptional regulation using a reporter gene assay

Study of gene expression can be facilitated by using a reporter gene assay. Instead of directly measuring the level of target gene mRNA, one can clone the promoter region of the gene of interest in front of a reporter gene and measure the reporter gene expression as a reflection of the expression of the gene of interest. We describe a simple lacZ-fusion system to measure the activity of the reporter gene product beta-galactosidase. Different strategies of making the fusion construct and their applications are also discussed. This method is particularly useful to dissect the promoter region of the gene of interest and is also used in other experimental protocols such as the yeast two-hybrid analysis.