Such genes are called reporters because the characteristics they confer on organisms expressing them are easily identified and measured, or because they are selectable markers.
For bacteria or prokaryotic cells in culture, this is usually in the form of a circular DNA molecule called a plasmid.
[1] Commonly used reporter genes that induce visually identifiable characteristics usually involve fluorescent and luminescent proteins.
Examples include the gene that encodes jellyfish green fluorescent protein (GFP), which causes cells that express it to glow green under blue or ultraviolet light,[2] the enzyme luciferase, which catalyzes a reaction with luciferin to produce light, and the red fluorescent protein from the gene dsRed [fr].
[11] Many methods of transfection and transformation – two ways of expressing a foreign or modified gene in an organism – are effective in only a small percentage of a population subjected to the techniques.
[19][20] Reporter gene assay have been increasingly used in high throughput screening (HTS) to identify small molecule inhibitors and activators of protein targets and pathways for drug discovery and chemical biology.
[24] A more complex use of reporter genes on a large scale is in two-hybrid screening, which aims to identify proteins that natively interact with one another in vivo.