Fluorescence is the process by which the fluorophore absorbs a stimulus such as light upon interaction. This causes a conformational change in the fluorophore where a longer wavelength is created via an energy transfer process. The lower emission of photons due to the change can be detected as an electrical signal. This phenomenon can be observed in aromatic biological proteins like tryptophan and tyrosine through the imidazole ring, allowing them to be synthesized in many environments. Williams, Slatko and McCarrey, 2007). Fluorescence was first discovered in Aequorea victoria, which synthesizes aquorin, a chemiluminescent protein. It is a luciferase that catalyzes the oxidation of coelenterazine through a calcium-dependent reaction to emit blue light and green fluorescence under UV light. Soon after, it was cloned and GFP was expressed in bacteria (Williams, Slatko, & McCarrey, 2007). Luciferase is a bacterial reporter present in certain species such as Photobacterium. Bioluminescence is produced from the dehydration of the hydroflavin intermediate, producing blue/green light. Mutations have been discovered that improve the efficiency of GFP, giving rise to enhanced fluorescent proteins (EGFP). The point mutation could then be used in mammalian cells due to increased stability. Similarly, other mutant color variants have been created from GFP homologs like marine corals, revolutionizing the understanding of diseases and many biological processes. The variances allow the use of color due to the unique β-barrel formation of FP. However, it can also negatively affect brightness and sensitivity (Kremers et al., 2011). One of the first uses of FP was for protein labeling. This allowed the expression and localization of prot...... middle of paper ......uh. It also causes hypersensitization and relocalization of fluorescence within tissues. This relocalization is thought to simply be due to a change in affinity for living and dead cells. With prolonged use of photosensitization, cell morphology may change (Serebrovskaya et al., 2009). The practical implication of green fluorescent proteins is vast, affecting the study from the genomic to the organismal level. This has had a huge impact on all of these areas of research with a huge range of techniques now available, all based on this concept. The potential of FPs was quickly realized and many limiting features were used to their advantage, as seen with FRAP. While many conventional uses have focused on enabling visualization of subcellular molecules/compartments, FP can be used in drug screening and as a drug itself..