Green fluorescent protein (GFP)

Green fluorescent protein is a small, naturally occurring fluorescent protein originally isolated from the jellyfish *Aequorea victoria*. It consists of approximately 238 amino acids and has a molecular weight of about 21–27 kDa depending on the variant[1][2][6]. The structure features an 11-stranded β-barrel ("β-can") with an internal α-helix running through its axis. This helix contains the chromophore—a unique three-amino-acid sequence (Ser65-Tyr66-Gly67)—that undergoes autocatalytic cyclization and oxidation to form the light-emitting center[4][7]. When exposed to blue or ultraviolet light, this chromophore emits bright green fluorescence. GFP is not a therapeutic target such as a receptor or enzyme; rather, it is widely used as a genetic marker in cell biology and biotechnology. Its fluorescence allows researchers to visualize gene expression, track proteins within living cells, monitor cellular events in real time, and develop biosensors[8][9]. Numerous engineered variants exist with altered spectral properties or improved stability. There are no known drugs that interact with GFP nor mechanisms of action relevant to drug targeting. It does not play direct roles in human disease but serves as an essential tool for biomedical research. Safety concerns are minimal since it is non-toxic and biologically inert when expressed in most model organisms. The entry "Green fluorescent protein" is technically incorrect if interpreted strictly as a therapeutic target because it does not fit standard categories like receptor or enzyme; instead, it functions exclusively as a research tool[4][8].

Other names

GFPavGFP (Aequorea victoria green fluorescent protein)enhanced GFP (EGFP)GFPmut1mEGFP