What is GFP? 

To the naked eye, every organism’s complex systems are invisible. The numerous components of any organism seem impossible to untangle in the jumble of overlapping, microscopic processes that form life. So, how have scientists tracked molecules through the body, uncovered the inner workings of cells, and created an understanding of nearly every biological system? The answer lies in part with the Green Fluorescent Protein (GFP). 

GFP is a protein that fluoresces under exposure to light around the ultraviolet range. That is, GFP glows green under ultraviolet light – the same light that comes from the sun. This protein was first discovered in Aequorea victoria, the crystal jelly, a species of jellyfish. GFP allows Aequorea victoria to exhibit bioluminescence, the emission of light by a living organism. In the 1960s, chemists and biologists successfully isolated the protein from Aequorea victoria DNA, allowing for its use in research.

Application of GFP

The fluorescent properties of GFP allow biologists to “tag” cells, molecules, and other objects of interest, following these structures through an entire organism. This offers a clear visualization of these objects throughout the body.

As a protein, GFP can be modified to fuse with other proteins or regulatory sequences (portions of nucleic acids capable of increasing or decreasing gene expression). This allows scientists to visualize gene expression, seeing when genes are active in organisms and how they physically emerge. That is, when genes produce typical proteins, they also produce GFP, providing an indicator of this activity. Developing a better understanding of gene expression opens the door to studying development, diseases, and the building blocks of life. 

In biomedical fields, scientists use GFP to track tumor development, track pathogens, and assess the function of drug therapies. In Cancer Immunology, GFP is used to form glowing tumors and monitor cancerous cells. The clear visualization GFP provides gives clarity to diagnoses and medical cases. For agricultural and environmental studies, biologists have engineered organisms to express GFP in response to specific environmental cues. As a result, scientists can track the effects of pollution or evaluate crop health across an environment. 

The Limitations of GFP 

Since GFP is a large protein, its usage, especially in fusing with other molecules, can be limited. Due to its large size, GFP can interfere with the functions of fused molecules. Furthermore, even with the current application of Enhanced GFP (eGFP) which is brighter and matures faster than the wild type, certain conditions can limit the brightness of GFP. For example, low expression of a gene tagged with GFP or application in deep tissues reduces GFP’s brightness and visualization.

Regardless of its limitations, GFP has proved and will continue to be a vital part of biological research. As scientific techniques and technology advance, GFP will find new and improved applications.

– Ethan Jing ’25