Editing Green fluorescent protein (section)

=== Reporter assays ===

Green fluorescent protein may be used as a [[reporter gene]].<ref>{{cite journal | vauthors = Jugder BE, Welch J, Braidy N, Marquis CP | title = Construction and use of a Cupriavidus necator H16 soluble hydrogenase promoter (PSH) fusion to gfp (green fluorescent protein) | journal = PeerJ | volume = 4 | pages = e2269 | date = 2016-07-26 | pmid = 27547572 | pmc = 4974937 | doi = 10.7717/peerj.2269 | doi-access = free }}</ref><ref name="pmid15596111">{{cite journal | vauthors = Arun KH, Kaul CL, Ramarao P | title = Green fluorescent proteins in receptor research: an emerging tool for drug discovery | journal = Journal of Pharmacological and Toxicological Methods | volume = 51 | issue = 1 | pages = 1–23 | year = 2005 | pmid = 15596111 | doi = 10.1016/j.vascn.2004.07.006 }}</ref>

For example, GFP can be used as a reporter for environmental toxicity levels. This protein has been shown to be an effective way to measure the toxicity levels of various chemicals including ethanol, ''p''-formaldehyde, phenol, triclosan, and paraben. GFP is great as a reporter protein because it has no effect on the host when introduced to the host's cellular environment. Due to this ability, no external visualization stain, ATP, or cofactors are needed. With regards to pollutant levels, the fluorescence was measured in order to gauge the effect that the pollutants have on the host cell. The cellular density of the host cell was also measured. Results from the study conducted by Song, Kim, & Seo (2016) showed that there was a decrease in both fluorescence and cellular density as pollutant levels increased. This was indicative of the fact that cellular activity had decreased. More research into this specific application in order to determine the mechanism by which GFP acts as a pollutant marker.<ref>{{cite journal | vauthors = Song YH, Kim CS, Seo JH | title = Noninvasive monitoring of environmental toxicity through green fluorescent protein expressing Escherichia coli. | journal = Korean Journal of Chemical Engineering | date = April 2016 | volume = 33 | issue = 4 | pages = 1331–6 | doi = 10.1007/s11814-015-0253-1 | s2cid = 62828580 }}</ref> Similar results have been observed in zebrafish because zebrafish that were injected with GFP were approximately twenty times more susceptible to recognize cellular stresses than zebrafish that were not injected with GFP.<ref name="pmid23143852">{{cite journal | vauthors = Pan Y, Leifert A, Graf M, Schiefer F, Thoröe-Boveleth S, Broda J, Halloran MC, Hollert H, Laaf D, Simon U, Jahnen-Dechent W | title = High-sensitivity real-time analysis of nanoparticle toxicity in green fluorescent protein-expressing zebrafish | journal = Small | location = Weinheim an Der Bergstrasse, Germany | volume = 9 | issue = 6 | pages = 863–9 | date = March 2013 | pmid = 23143852 | doi = 10.1002/smll.201201173 }}</ref>

==== Advantages ====

The biggest advantage of GFP is that it can be heritable, depending on how it was introduced, allowing for continued study of cells and tissues it is expressed in. Visualizing GFP is noninvasive, requiring only illumination with blue light. GFP alone does not interfere with biological processes, but when fused to proteins of interest, careful design of linkers is required to maintain the function of the protein of interest. Moreover, if used with a monomer it is able to diffuse readily throughout cells.<ref name="pmid19553219">{{cite journal | vauthors = Chalfie M | title = GFP: Lighting up life | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 106 | issue = 25 | pages = 10073–10080 | date = Jun 2009 | pmid = 19553219 | doi = 10.1073/pnas.0904061106 | pmc=2700921| bibcode = 2009PNAS..10610073C | doi-access = free }}</ref>