Difference Between GFP and EGFP

The key difference between GFP and EGFP is that the GFP is a wild-type protein incorporated in the molecular cloning of non-mammalian cells while the EGFP is an improved or engineered type of GFP that can be used on mammalian cells.

Molecular cloning is an advanced technique that scientists use immensely in expressing proteins via recombinant technology. In recombinant DNA technology, it is necessary to transform recombinant vector successfully to host organism. Hence, during the transformation process, it should be identified and confirmed whether the gene of interest has been transformed or not to the host. To assess this, molecular biologists adopt several techniques. Out of those techniques, one is reporter gene. These reporter genes act as selectable markers to select the correct transformants. Thus, the Green Fluorescent Protein (GFP) and Enhanced Green Fluorescent Protein (EGFP) are two reporter proteins used in molecular cloning.

1. Overview and Key Difference
2. What is GFP
3. What is EGFP
4. Similarities Between GFP and EGFP
5. Side by Side Comparison – GFP vs EGFP in Tabular Form
6. Summary

What is GFP?

GFP is a wild-type protein that contains 238 amino acid residues and several selectable regions of amino acid sequences that distinguish it from the other fluorescent proteins. Furthermore, this wild-type protein was originally in isolation from Aequorea Victoria; a type of jellyfish. However, in natural phenomena, the jellyfish was able to produce green colour fluorescence in response to certain stimuli.

Earlier, this concept surprised the scientists, and they decided to use it on their recombinant DNA technologies. Consequently, scientists used this mutant form of the wild-type gene as a reporter gene in their gene expression studies. The wild-type gene of GFP is capable of producing a protein which gives fluorescence at room temperature or under UV light. Therefore, when inserted into the transformants, it expresses and produces fluorescence. If the fluorescence results after the transformation process, it confirms the success of the transformation process. In simple words, fluorescence emission signals the successful transformation of the vector that carries the gene of interest into the host.

Figure 01: GFP

Because of this reason, the GFP acts as an in vivo marker of gene expression. At present, genetic engineering techniques are in use to produce GFP. Also, many improved versions of GFP such as EGFP are available. Hence, this enables efficient use of the GFP in molecular cloning and gene expression studies.

What is EGFP?

Enhanced Green Fluorescent Protein or EGFP is an improved version of GFP. In simple words, we can define EGFP as an engineered version of wild-type GFP. When the wild-type gene of GFP mutates, it produces beneficial effects. Hence, the mutated gene of GFP allows the expression of new characters, and as a result of that, we can produce Enhanced GFP with improved characteristics. Furthermore, we can introduce mutations successfully in to the wild-type GFP gene using irradiation or chemical methods. These mutated genes then produce the EGFP, which has more beneficial characteristics.

Figure 02: EGFP

The improved characteristics of EGFP are as follows;

Able to emit stronger fluorescence signals.
Has high sensitivity.
Can use it on mammalian cells instead of prokaryotes and other lower level eukaryotes.
Also, provides increased purity of the product.

Therefore, in comparison to GFP, EGFP is the preferred choice for gene expression studies. However, the product is more expensive in comparison to GFP.

What are the Similarities Between GFP and EGFP?

GFP and EGFP are two proteins which have the ability to emit green colour
Therefore, both function as reporter proteins in gene expression studies.
Also, it is possible to synthesize both using recombinant DNA technology.
Moreover, it is easy to further mutate these two types to synthesize improved forms.

What is the Difference Between GFP and EGFP?

The reporter gene is a gene that attaches with the gene of interest in recombinant DNA technology. It signals the successful transformation of the recombinant vector to the host. Here, GFP and EGFP are two types of green florescent proteins that work as reporter proteins. However, the key difference between GFP and EGFP is that the GFP is a wild-type while EGFP is an engineered version of GFP. Furthermore, EGFP has more beneficial characteristics than GFP. For example, EGFP produces stronger fluorescent light and is more sensitive than the GFP. Another difference between GFP and EGFP is the systems in which we can use these. Non-mammalian systems use GFP while mammalian systems use EGFP.

The below infographic presents the difference between GFP and EGFP in tabular form.

Summary – GFP vs EGFP

GFP and EGFP are reporter proteins in molecular cloning and gene expression studies. GFP is the wild-type protein, which is a green fluorescent protein. The protein was initially in isolation from the jellyfish Aequorea victoria. In contrast, EFGP is an enhanced form of GFP protein. It is a mutant of the wild-type with improved characteristics. Hence, EFGP has the higher signal strength and higher sensitivity. Therefore, we can use it on mammalian vectors. In contrast, the use of GFP is mainly only on non – mammalian vectors. In over all, this is the difference between GFP and EGFP.

Reference:

1.Cinelli, R A, et al. “The Enhanced Green Fluorescent Protein as a Tool for the Analysis of Protein Dynamics and Localization: Local Fluorescence Study at the Single-Molecule Level.” Photochemistry and Photobiology., U.S. National Library of Medicine, June 2000. Available here
2.“PDB101: Molecule of the Month: Green Fluorescent Protein (GFP).” RCSB: PDB-101. Available here

Image Courtesy:

1.”GFP Fluorescent Protein Movie”By Erin Rod – Own work, (CC BY-SA 4.0) via Commons Wikimedia
2.”CA2 amigo2 eGFP mouse”By Dudek, Serena; Curuana, Douglas; Carstens, Kelly – Own work, (CC BY-SA 3.0) via Commons Wikimedia