Green fluorescent protein

Green fluorescent protein (GFP) is a protein isolated from the jellyfish Aequorea victoria that emits green light after absorbing blue or ultraviolet light. Its fluorescence enables direct visualization of gene expression and cellular processes.

Fluorescence: The emission of light by a substance after it absorbs electromagnetic radiation. GFP’s green signal is fluorescence triggered by absorbed light.
Green fluorescent protein tagging: A method that fuses GFP to a protein so its location or movement can be observed through fluorescence. A GFP fusion lets researchers track a chosen protein in cells.
Aequorea victoria: A bioluminescent jellyfish species found in the northeastern Pacific Ocean. GFP was first isolated from this jellyfish.
Red fluorescent protein: A class of fluorescent proteins that emit red light and can be genetically encoded as biological markers. Red emission can be paired with GFP to distinguish multiple targets.
Chromophore: The light-absorbing part of a molecule that gives it color or enables it to emit light. A formed chromophore inside GFP produces its characteristic fluorescence.
Reporter gene: A gene whose measurable product indicates the activity of a regulatory sequence or biological process. GFP is a reporter when its fluorescence reveals gene expression.
Osamu Shimomura: A Japanese-American organic chemist who discovered aequorin and isolated green fluorescent protein from Aequorea victoria. His work identified GFP while investigating jellyfish bioluminescence.
Luciferase: An enzyme that catalyzes light-producing reactions using a luciferin substrate. Unlike GFP, luciferase produces light through a chemical reaction rather than fluorescence.
Protein folding: The process by which a protein adopts the three-dimensional structure needed for its activity. GFP’s barrel-shaped fold protects the chromophore and enables fluorescence.
Fluorescence microscopy: Microscopy that uses emitted light from fluorescent molecules to image structures or processes. It detects GFP-tagged structures with spatial detail.

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