What's GFP - the Magic Fluorescent Protein?

Much of the bright fluorescence in corals and their relatives originates from proteins that belong to a group now referred to as 'green fluorescent protein' (GFP). Green is certainly the most common color found in these animals, but there are many other colors, red, for example. The name is tied up in the history of the discovery of these special proteins in Aequorea victoria, a bioluminescent jellyfish, and is now used to refer loosely to the entire family of related proteins, no matter what color they fluoresce.

Most natural fluorescence does not come directly from a protein, but from other molecules that are attached after the protein has been made by the cell. This means that in order to become fluorescent not only would an organism have to make the right protein, but would also need to do some additional chemistry, having the right substances available to the protein. What is magic about GFP is that the fluorescence comes directly from the protein itself, with no additional chemistry needed. If a cell makes the protein, it becomes fluorescent. This property makes GFP invaluable for a wide range of applications in biomedical and genetic research, where it serves as a marker for genetic activity. Several companies now sell enhancement green fluorescent protein (EGFP) plasmid.