RESEARCH STARTER

Green fluorescent protein (GFP)

Green fluorescent protein (GFP) is a bioluminescent protein originally found in the Aequorea victoria jellyfish, known for its ability to emit a green glow when exposed to blue light. Discovered in 1962, GFP has since become a crucial tool in molecular and cellular biology, allowing scientists to track proteins, visualize cellular processes, and study gene expression. When GFP is attached to a target protein, it fluoresces green under ultraviolet light, facilitating the observation of biological pathways and interactions within cells.

GFP is composed of 238 amino acids and functions without the need for complex chemical processes, making it easier to use compared to other fluorescent markers. In addition to its scientific applications, GFP has been utilized in creating genetically modified organisms, including glow-in-the-dark fish known as GloFish. These fish were engineered to glow as an indicator of environmental pollutants. While GFP has found extensive use in research and biotechnology, its commercialization in some regions is restricted due to regulations concerning genetically modified organisms. The collaborative efforts of scientists such as Osamu Shimomura, Martin Chalfie, and Roger Tsien in advancing GFP research were recognized with the Nobel Prize in Chemistry in 2008, highlighting its significance in the field.

Full Article

The green fluorescent protein (GFP) is a fluorescent protein found in the Aequorea victoria jellyfish. Bioluminescence is a form of light triggered by biochemical reactions emitted by living creatures. In the case of A. victoria, which is also known as the crystal jellyfish, a blue light is emitted by a photoprotein called aequorin. GFP converts this light into a green color. Solutions containing GFP appear yellow under laboratory lights but turn green again when exposed to ultraviolet or blue light due to fluorescence.

Since its discovery in 1962, GFP has proven invaluable to scientists as a biological marker. When attached correctly to any element of high-enough concentration within a cell—such as a virus or a protein—these parts will glow green under appropriate excitation when viewed under a microscope. As a result, scientists can easily understand the marked proteins’ pathways, structures, processes, and interactions with other proteins within an organic structure. GFP is among the most studied proteins in biology and has many applications. It is primarily used as a marker in various forms of research, though doctors hope a version of GFP might someday be used to detect the presence of tumors in humans. GFP is also used in gene expression research, the development of biosensors, and optogenetics.

Background

While working as a research assistant at Nagoya University in Japan, Japanese scientist Osamu Shimomura discovered the biological process that caused a tiny crustacean known as the sea-firefly (Vargula hilgendorfii) to glow when wet. Learning of his research, American biologist Frank Johnson recruited Shimomura to work at Princeton University to examine the mechanisms behind A. victoria’s bioluminescence.

When Shimomura and his colleagues purified the bioluminescent elements in the jellyfish, they discovered aequorin, a type of photoprotein that causes blue bioluminescence when it binds with calcium. Photoproteins, like aequorin, are a form of enzyme composed of protein molecules. Further research into the processes used by aequorin to glow demonstrated the presence of a second protein, GFP, which cast a green fluorescent color after it absorbed the blue light produced by aequorin. By 1962, Shimomura was able to isolate the part of the green-glowing protein that was responsible for its fluorescent abilities. In 1971, researchers John W. Hastings and James G. Morin named the new protein green fluorescent protein during their studies of aequorin.

During the course of the next decade, Shimomura was able to develop a process to purify GFP. These discoveries enabled him to describe the structure of GFP and its underlying properties. Eventually, Shimomura lost interest in further studying GFP and completed his final research on the protein by 1979.

Shimomura’s initial research was later expanded by American neurobiologist Martin Chalfie and Chinese American biochemist Roger Tsien. Chalfie was the first researcher to understand the potential applications of GFP as a marker. In 1992, he discovered that when inserted into the bacterium Escherichia coli, the GFP gene naturally produced GFP without any further enhancements. Tsien later reengineered the GFP-producing gene so that it could be naturally produced in other structures. Tsien was able to develop forms of GFP that demonstrated brighter fluorescence and responded to new ranges of wavelengths. In addition, he developed GFP variants that produced other colors so that multiple colors of GFP could be used to mark different components within the same sample. Together, Shimomura, Chalfie, and Tsien were honored with the 2008 Nobel Prize in chemistry for their work with GFP.

In 2022, cancer researchers in Japan and the United States published their review of research on tumor-targeted fluorescence labeling systems that used GFP and other fluorescent proteins to evaluate the systems’ effectiveness in diagnosing and treating cancer. The researchers concluded that although there were obstacles to using optical imaging techniques to study the distribution of tumor cells in the human body, tumor-targeted fluorescence labeling systems held promise for detecting tumor cells.

Overview

GFP is composed of 238 amino acids, which are the basic building blocks of all proteins. GFP is contained within three of these amino acids—numbers sixty-five, sixty-six, and sixty-seven. This form of protein has existed within the A. victoria jellyfish for an estimated 60 million years. A. victoria is a small transparent jellyfish found off the West Coast of the United States. It is bell-shaped with a ring of tentacles hanging off its outer edges. The jellyfish feed off microorganisms such as zooplankton and the larval forms of many larger organisms.

GFP has proven to be easy to use. Typically, most light-creating proteins use special molecules called chromophores to capture and release photons, which are particles that transmit light. As a result, when used as markers in laboratory settings, these synthesized chromophores must be specially constructed or designed and then carefully bound with the sample’s acceptor molecules (e.g., fluorescent-producing proteins). Since GFP is naturally occurring, it does not require any extra effort to make it a suitable marker. All it needs to work is oxygen. The resulting fluorescence is readily detectable under any ultraviolet light. By contrast, other markers often need added enzymes or substrates to work properly. This ease of use has made GFP one of the most widely used fluorescent markers in science.

GFP has other marketable uses. For instance, GFP is one of several fluorescent genes that have been inserted into zebrafish to create different colors of glow-in-the-dark fish for the pet industry. These fish were created by microinjecting a version of the gene that creates GFP into fertilized fish embryos. The resulting fish and their descendants carry the gene that causes them to fluoresce. By introducing GFP at this stage of biological development, the fish embryo was able to naturally incorporate the gene into its genome. The fish were originally developed by Singaporean researchers in order to create biomechanisms that could serve as indicators of pollution. They hoped to create a type of fluorescence that would glow in the presence of environmental toxins, thereby providing an easy method of testing the levels of pollution in water. Animals like the zebrafish that have been altered using genetic engineering techniques are called transgenic organisms. Many advances in GFP include AI-designed fluorescent proteins, such as esmGFP, which are created computationally and do not occur in nature, expanding beyond naturally derived or modified GFP variants. Research has also expanded the use of fluorescent proteins beyond simple markers, enabling time-resolved imaging, multiplex imaging of multiple cellular processes, and improvements in super-resolution microscopy. Related developments have extended GFP-based fluorescence to fields such as forensic science, where similar compounds are used in techniques like rapid fingerprint detection.

An American company called Yorktown Technologies learned of the Singaporean fish and signed a deal with their developers to sell the resulting animals as pets. Marketed as GloFish, they are sold throughout the United States. Glowing angelfish, tetras, rainbow sharks, and tiger barbs have also been developed. Researchers have expanded the effect in other species of fish. As they are legally classified as genetically modified organisms, laws in Australia, New Zealand, and the European Union restrict or prohibit their sale in those locations. However, studies of genetically modified zebrafish have shown no risk of contamination to either natural zebrafish or the environment.


Bibliography

Devlin, Hannah. “Forensic Spray Using Jellyfish Protein Could Speed Up Fingerprint Detection.” The Guardian, 3 Mar. 2024, www.theguardian.com/science/2024/mar/03/forensic-spray-using-jellyfish-protein-could-speed-up-fingerprint-detection. Accessed 18 Mar. 2026.

Goodsell, David. “Green Fluorescent Protein (GFP).” Protein Data Bank, June 2003, pdb101.rcsb.org/motm/42. Accessed 18 Mar. 2026.

March, J. C., et al. “Biotechnological Applications of Green Fluorescent Protein.” Applied Microbiology and Biotechnology, vol. 62, no. 4, Sept. 2003, pp. 303–15.

McDowall, Jennifer. “Green Fluorescent Protein.” InterPro, June 2003, www.ebi.ac.uk/interpro/potm/2003_1/Page_1.htm. Accessed 20 Feb. 2025.

Ohba, Yusuke, et al. “Fluorescent Protein-Based Biosensors and Their Clinical Applications.” Progress in Molecular Biology and Translational Science, vol. 113, 2013, pp. 313–48.

Patrick, Marcy. “Fluorescent Proteins 101: Green Fluorescent Protein (GFP).” Addgene, 15 May 2014, blog.addgene.org/plasmids-101-green-fluorescent-protein-gfp. Accessed 18 Mar. 2026.

Sundaram, Jeyashree. “GFP Applications.” Medical Life Sciences News, 26 Feb. 2019, www.news-medical.net/life-sciences/GFP-Applications.aspx. Accessed 18 Mar. 2026.

Swayne, Matt. “AI Simulates 500 Million Years of Evolution to Design Shiny New Proteins.” The AI Insider, 31 Jan. 2025, theaiinsider.tech/2025/01/31/ai-simulates-500-million-years-of-evolution-to-design-shiny-new-proteins/. Accessed 18 Mar. 2026.

Tan, Zizhu, et al. “Time-Resolved Fluorescent Proteins Expand Fluorescent Microscopy in Temporal and Spectral Domains.” Cell, vol. 188, no. 24, 26 Nov. 2025, pp. 6987–7005.e28, doi:10.1016/j.cell.2025.01027-X. Accessed 18 Mar. 2026.

Tazawa, Hiroshi, et al. “Tumor-Targeted Fluorescence Labeling Systems for Cancer Diagnosis and Treatment.” Cancer Science, vol. 113, no. 6, 2022, doi:10.1111/cas.15369. Accessed 18 Mar. 2026.

Tsien, Roger Y. “The Green Fluorescent Protein.” Annual Review of Biochemistry, vol. 67, 1998, pp. 509–44.

Zimmer, Marc. “Our Research.” Green Fluorescent Protein, Green Fluorescent Protein, Connecticut College, 2025, gfp.conncoll.edu. Accessed 18 Mar. 2026.

Zou, Yawen. “Green Fluorescent Protein.” The Embryo Project Encyclopedia, 11 June 2014, embryo.asu.edu/pages/green-fluorescent-protein. Accessed 18 Mar. 2026.

Full Article

The green fluorescent protein (GFP) is a fluorescent protein found in the Aequorea victoria jellyfish. Bioluminescence is a form of light triggered by biochemical reactions emitted by living creatures. In the case of A. victoria, which is also known as the crystal jellyfish, a blue light is emitted by a photoprotein called aequorin. GFP converts this light into a green color. Solutions containing GFP appear yellow under laboratory lights but turn green again when exposed to ultraviolet or blue light due to fluorescence.

Since its discovery in 1962, GFP has proven invaluable to scientists as a biological marker. When attached correctly to any element of high-enough concentration within a cell—such as a virus or a protein—these parts will glow green under appropriate excitation when viewed under a microscope. As a result, scientists can easily understand the marked proteins’ pathways, structures, processes, and interactions with other proteins within an organic structure. GFP is among the most studied proteins in biology and has many applications. It is primarily used as a marker in various forms of research, though doctors hope a version of GFP might someday be used to detect the presence of tumors in humans. GFP is also used in gene expression research, the development of biosensors, and optogenetics.

Background

While working as a research assistant at Nagoya University in Japan, Japanese scientist Osamu Shimomura discovered the biological process that caused a tiny crustacean known as the sea-firefly (Vargula hilgendorfii) to glow when wet. Learning of his research, American biologist Frank Johnson recruited Shimomura to work at Princeton University to examine the mechanisms behind A. victoria’s bioluminescence.

When Shimomura and his colleagues purified the bioluminescent elements in the jellyfish, they discovered aequorin, a type of photoprotein that causes blue bioluminescence when it binds with calcium. Photoproteins, like aequorin, are a form of enzyme composed of protein molecules. Further research into the processes used by aequorin to glow demonstrated the presence of a second protein, GFP, which cast a green fluorescent color after it absorbed the blue light produced by aequorin. By 1962, Shimomura was able to isolate the part of the green-glowing protein that was responsible for its fluorescent abilities. In 1971, researchers John W. Hastings and James G. Morin named the new protein green fluorescent protein during their studies of aequorin.

During the course of the next decade, Shimomura was able to develop a process to purify GFP. These discoveries enabled him to describe the structure of GFP and its underlying properties. Eventually, Shimomura lost interest in further studying GFP and completed his final research on the protein by 1979.

Shimomura’s initial research was later expanded by American neurobiologist Martin Chalfie and Chinese American biochemist Roger Tsien. Chalfie was the first researcher to understand the potential applications of GFP as a marker. In 1992, he discovered that when inserted into the bacterium Escherichia coli, the GFP gene naturally produced GFP without any further enhancements. Tsien later reengineered the GFP-producing gene so that it could be naturally produced in other structures. Tsien was able to develop forms of GFP that demonstrated brighter fluorescence and responded to new ranges of wavelengths. In addition, he developed GFP variants that produced other colors so that multiple colors of GFP could be used to mark different components within the same sample. Together, Shimomura, Chalfie, and Tsien were honored with the 2008 Nobel Prize in chemistry for their work with GFP.

In 2022, cancer researchers in Japan and the United States published their review of research on tumor-targeted fluorescence labeling systems that used GFP and other fluorescent proteins to evaluate the systems’ effectiveness in diagnosing and treating cancer. The researchers concluded that although there were obstacles to using optical imaging techniques to study the distribution of tumor cells in the human body, tumor-targeted fluorescence labeling systems held promise for detecting tumor cells.

Overview

GFP is composed of 238 amino acids, which are the basic building blocks of all proteins. GFP is contained within three of these amino acids—numbers sixty-five, sixty-six, and sixty-seven. This form of protein has existed within the A. victoria jellyfish for an estimated 60 million years. A. victoria is a small transparent jellyfish found off the West Coast of the United States. It is bell-shaped with a ring of tentacles hanging off its outer edges. The jellyfish feed off microorganisms such as zooplankton and the larval forms of many larger organisms.

GFP has proven to be easy to use. Typically, most light-creating proteins use special molecules called chromophores to capture and release photons, which are particles that transmit light. As a result, when used as markers in laboratory settings, these synthesized chromophores must be specially constructed or designed and then carefully bound with the sample’s acceptor molecules (e.g., fluorescent-producing proteins). Since GFP is naturally occurring, it does not require any extra effort to make it a suitable marker. All it needs to work is oxygen. The resulting fluorescence is readily detectable under any ultraviolet light. By contrast, other markers often need added enzymes or substrates to work properly. This ease of use has made GFP one of the most widely used fluorescent markers in science.

GFP has other marketable uses. For instance, GFP is one of several fluorescent genes that have been inserted into zebrafish to create different colors of glow-in-the-dark fish for the pet industry. These fish were created by microinjecting a version of the gene that creates GFP into fertilized fish embryos. The resulting fish and their descendants carry the gene that causes them to fluoresce. By introducing GFP at this stage of biological development, the fish embryo was able to naturally incorporate the gene into its genome. The fish were originally developed by Singaporean researchers in order to create biomechanisms that could serve as indicators of pollution. They hoped to create a type of fluorescence that would glow in the presence of environmental toxins, thereby providing an easy method of testing the levels of pollution in water. Animals like the zebrafish that have been altered using genetic engineering techniques are called transgenic organisms. Many advances in GFP include AI-designed fluorescent proteins, such as esmGFP, which are created computationally and do not occur in nature, expanding beyond naturally derived or modified GFP variants. Research has also expanded the use of fluorescent proteins beyond simple markers, enabling time-resolved imaging, multiplex imaging of multiple cellular processes, and improvements in super-resolution microscopy. Related developments have extended GFP-based fluorescence to fields such as forensic science, where similar compounds are used in techniques like rapid fingerprint detection.

An American company called Yorktown Technologies learned of the Singaporean fish and signed a deal with their developers to sell the resulting animals as pets. Marketed as GloFish, they are sold throughout the United States. Glowing angelfish, tetras, rainbow sharks, and tiger barbs have also been developed. Researchers have expanded the effect in other species of fish. As they are legally classified as genetically modified organisms, laws in Australia, New Zealand, and the European Union restrict or prohibit their sale in those locations. However, studies of genetically modified zebrafish have shown no risk of contamination to either natural zebrafish or the environment.


Bibliography

Devlin, Hannah. “Forensic Spray Using Jellyfish Protein Could Speed Up Fingerprint Detection.” The Guardian, 3 Mar. 2024, www.theguardian.com/science/2024/mar/03/forensic-spray-using-jellyfish-protein-could-speed-up-fingerprint-detection. Accessed 18 Mar. 2026.

Goodsell, David. “Green Fluorescent Protein (GFP).” Protein Data Bank, June 2003, pdb101.rcsb.org/motm/42. Accessed 18 Mar. 2026.

March, J. C., et al. “Biotechnological Applications of Green Fluorescent Protein.” Applied Microbiology and Biotechnology, vol. 62, no. 4, Sept. 2003, pp. 303–15.

McDowall, Jennifer. “Green Fluorescent Protein.” InterPro, June 2003, www.ebi.ac.uk/interpro/potm/2003_1/Page_1.htm. Accessed 20 Feb. 2025.

Ohba, Yusuke, et al. “Fluorescent Protein-Based Biosensors and Their Clinical Applications.” Progress in Molecular Biology and Translational Science, vol. 113, 2013, pp. 313–48.

Patrick, Marcy. “Fluorescent Proteins 101: Green Fluorescent Protein (GFP).” Addgene, 15 May 2014, blog.addgene.org/plasmids-101-green-fluorescent-protein-gfp. Accessed 18 Mar. 2026.

Sundaram, Jeyashree. “GFP Applications.” Medical Life Sciences News, 26 Feb. 2019, www.news-medical.net/life-sciences/GFP-Applications.aspx. Accessed 18 Mar. 2026.

Swayne, Matt. “AI Simulates 500 Million Years of Evolution to Design Shiny New Proteins.” The AI Insider, 31 Jan. 2025, theaiinsider.tech/2025/01/31/ai-simulates-500-million-years-of-evolution-to-design-shiny-new-proteins/. Accessed 18 Mar. 2026.

Tan, Zizhu, et al. “Time-Resolved Fluorescent Proteins Expand Fluorescent Microscopy in Temporal and Spectral Domains.” Cell, vol. 188, no. 24, 26 Nov. 2025, pp. 6987–7005.e28, doi:10.1016/j.cell.2025.01027-X. Accessed 18 Mar. 2026.

Tazawa, Hiroshi, et al. “Tumor-Targeted Fluorescence Labeling Systems for Cancer Diagnosis and Treatment.” Cancer Science, vol. 113, no. 6, 2022, doi:10.1111/cas.15369. Accessed 18 Mar. 2026.

Tsien, Roger Y. “The Green Fluorescent Protein.” Annual Review of Biochemistry, vol. 67, 1998, pp. 509–44.

Zimmer, Marc. “Our Research.” Green Fluorescent Protein, Green Fluorescent Protein, Connecticut College, 2025, gfp.conncoll.edu. Accessed 18 Mar. 2026.

Zou, Yawen. “Green Fluorescent Protein.” The Embryo Project Encyclopedia, 11 June 2014, embryo.asu.edu/pages/green-fluorescent-protein. Accessed 18 Mar. 2026.

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