Yellow fluorescent protein
Yellow fluorescent protein (YFP) is a yellow version of green fluorescent protein (GFP) taken from the jellyfish Aequorea victoria. It is excited by light around 513 nm and emits light at about 527 nm, giving a yellow glow. Because its color is different from GFP, researchers can label and study multiple proteins at the same time in the same sample.
YFP was created by mutating GFP. The most important change is at residue 203, where threonine is replaced by tyrosine (T203Y), which shifts the color toward yellow. In total, four mutations were used to turn GFP into YFP.
Several improved YFP variants exist, including Citrine, Venus, and YPet. These variants are brighter, mature faster, and are less sensitive to chloride. Venus, for example, adds F46L along with other substitutions (F64L, M153T, V163A, S175G) to improve folding and tolerance to acid and chloride; F46L also helps the chromophore form faster at 37°C.
YFP is commonly used as the acceptor in FRET sensors, with donors such as monomeric cyan fluorescent protein (mCFP).
In short, YFP is a yellow-colored GFP mutant created by several mutations, with newer variants that are brighter and more robust for biological research.
This page was last edited on 2 February 2026, at 23:20 (CET).