EGFP

Enhanced Green Fluorescent Protein (EGFP) is a widely used variant of the Green Fluorescent Protein (GFP), originally derived from the jellyfish Aequorea victoria. EGFP has become an essential tool in molecular and cellular biology due to its bright green fluorescence when exposed to blue or ultraviolet light. This article delves into the background, structure, properties, and applications of EGFP.

GFP was first isolated from Aequorea victoria and consists of 238 amino acids. The protein exhibits intense green fluorescence, making it a valuable reporter for gene expression and protein localization studies . EGFP was developed to enhance the fluorescence and stability of the original GFP. It contains two key mutations, F64L and S65T, which significantly increase its fluorescence intensity and folding efficiency at 37°C .

EGFP is a non-glycosylated, homodimeric protein with a molecular mass of approximately 26.9 kDa . It is composed of 239 amino acids and has an isoelectric point of 6.2 . The protein’s fluorescence is due to a chromophore formed by the cyclization and oxidation of three amino acids: serine, tyrosine, and glycine. EGFP exhibits an excitation peak at 488 nm and an emission peak at 507 nm, making it suitable for use with standard fluorescence microscopy and flow cytometry .

EGFP is extensively used in various biological and biomedical research applications, including:

1. Gene Expression Studies: EGFP is commonly used as a reporter gene to monitor the expression of target genes in living cells and organisms.
2. Protein Localization: By fusing EGFP to proteins of interest, researchers can visualize the subcellular localization and dynamics of these proteins in real-time.
3. Cell Tracking: EGFP-labeled cells can be tracked in vivo to study cell migration, differentiation, and tissue regeneration.
4. Biosensing: EGFP can be used in biosensors to detect changes in cellular environments, such as pH, ion concentrations, and the presence of specific molecules .

EGFP offers several advantages over the original GFP, including higher fluorescence intensity, faster maturation, and improved stability at physiological temperatures . However, it also has some limitations, such as moderate acid sensitivity and the potential for weak dimerization .