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The main difference between GFP and YFP is that GFP is a fluorescent protein which has been isolated from jellyfish whereas YFP is a genetic mutant of the GFP.

Key Differences

GFP exhibits an excitation peak at 395 nm wavelength whereas shows excitation peak at 515 nm.
Harlon Moss
Sep 26, 2022
GFP exhibits an emission peak at 509 nm whereas YFP shows an emission peak at 527 nm.
Samantha Walker
Sep 26, 2022
GFP is used as a reporter of expression whereas YFP is used as acceptors for FRET sensors.
GFP stands for Green Fluorescent Protein whereas YFP stands for Yellow Fluorescent Protein.
GFP emits green colored light whereas YFP emits yellow colored light.
GFP has derived from jellyfish Aequorea Victoria whereas YFP is a mutant of the originally derived GFP.

Comparison Chart


It is the fluorescent protein which has been isolated from the jellyfish
It is a genetic mutant of the GFP

Stands for

Green Fluorescent Protein
Yellow Fluorescent Protein


Naturally found in many marine organisms
A genetic mutant of GFP

Excitation Peak

Major excitation peak at 395 nm And minor excitation peak at475 nm
Excitation peak at 515 nm
Samantha Walker
Sep 26, 2022

Emission Peak

Emission peak at 509 nm
Emission peak at 527 nm
Samantha Walker
Sep 26, 2022


· Used as a reporter of expression · Used to visualize the localization of the fused protein
· Used as non-invasive intracellular pH biosensors · Fluorescent indicator for local Ca2+ concentration


GFP is beneficial in cell and molecular biology. It is used as a reporter of expression. Reporter genes are used by scientists and researchers to attach to another gene which they are studying. GFP helps in measuring and indicating whether a gene has been expressed by an organism cell or population. This protein is also used as biosensors. YFP proteins are used as acceptors for FRET sensors. FRET stands for Fluorescent Resonance energy transfer. They are also called EET or RET electronic energy transfer and resonance energy transfer. It is a process which describes the energy transfer between 2 chromophores.

What is GFP?

GFP or Green Fluorescent Protein is bioluminescent polypeptide protein naturally found in marine animals such as jellyfish Aequorea victoria. In Aequorea, it is called aequorin. The main characteristic of GFP is that when it is exposed to blue ultraviolet light, it shows a green fluorescence. This protein is composed of 238 amino acids which are attached with each other through a peptide bond, and the size of the protein is 26.7 kDa. Protein folds to form the shape of a beta barrel. The part of the protein that makes it fluorescent is developed from the conjugation of the central chain atoms, Tyr66, Ser65, and Gly67, forming the highly conjugated, planar chromophore in the presence of oxygen. This chromophore is packed inside the beta-barrel structure, protecting the chromophore from quenching through paramagnetic oxygen, water dipoles or cis-trans isomerization. Noncovalent relations of the chromophore with the neighboring molecules increase its spectral properties.

Fluorescent proteins have two peaks which are an excitation peak and an emission peak. It shows an excitation peak at 395 nm wavelength and an emission peak at 509 nm wavelength. It means, this protein completely absorbs blue light at 475 nm or the 395 nm light in the long UV range and emits green light at 509 nm. 509 nm in the visible region is the lower green part. The quantum yield of the green fluorescent protein is 0.79. QY refers to the number of times an event occurs when a radiation-induced process takes place per photon. An event refers to the emission of photons.

What is YFP?

YFP refers to the Yellow Fluorescent Protein which is a mutant of the originally derived from GFP from the jellyfish Aequorea Victoria. It has two different peaks; emission peak at 527 nm and its excitation peak at 515 nm. The applications of YFP are same as GFP in molecular biology. Yellow fluorescent protein has three versions, Venus, citrine, and Yet. The specific properties of these improved versions are that they have chloride sensitivity which is reduced and it has a faster maturation and increased brightness due to quantum yield. It is a color which is a mutant accomplished by the T203Y mutation. This results in pi electron stacking interactions between the substituted tyrosine and the chromophore. Therefore, YFP absorbs green light at 514 nm wavelength while emitting yellow color light 527 nm. The importance of YFP in molecular biology is to serve as the acceptor for genetically coded Forster resonance energy transfer sensors. Hence, the most common donor fluorescent protein is a monomeric cyan fluorescent protein which another GFP derivative.

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