Promoter-reporter fusion

A promoter-reporter fusion is a technique used to determine the DNA sequences within a promoter region that are responsible for regulating transcription. The promoter region of interest is fused to a reporter gene: a gene that codes for a protein product that can easily be detected, such as a fluorescent protein.

The general method of promoter-reporter fusion is:

1. Clone the gene containing the promoter region that you want to examine;
2. Cut the cloned gene into fragments with a suitable restriction enzyme;
3. Ligate the promoter into a plasmid containing a promoter-less reporter gene;
4. Use the recombinant plasmids to transform a suitable host;
5. Assay the transformants for reporter gene activity.

By performing a series of deletions on the promoter region, and observing reporter gene activity, it is possible to determine precisely which DNA sequences are needed to regulate transcription of the gene.