Green Fluorescent Protein (GFP) has existed for more than one hundred and sixty million years in one species of jellyfish, Aequorea victoria. The protein is found in the photoorgans of Aequorea, see picture below right. GFP is not responsible for the glow often seen in pictures of jellyfish - that "fluorescence" is actually due reflection of the flash used to photograph the jellies.



GFP is an extraordinary protein in many respects: It is fluorescent and its fluorophore is made up of modified amino acid residues. Moreover it is the first known example of a Forster cycle within the core of a protein. Furthermore its crystal structure has recently been solved and the protein turned out to have a new structural motif, called the beta-can. On the following pages I will set out to discuss some of the most interesting features of this unique protein, starting out with its function in the introduction, followed by a view on the more or less isolated chromophore and finally presenting the three-dimensional structure of this fascinating protein.

What is the cause of this fluorescence? A protein that transduces the blue light into green fluorescent light. Our goal here is using these tools to understand sequence and other forms of GFP. Moreover, we further utilize the tool to look closer to the 3D structure of GFP.

Source:
Structure and Function of Green Fluorescent Protein