{{Short description|Protein which acts as a fluorophore}} {{Infobox nonhuman protein |Name=Red fluorescent protein drFP583 |Organism=Discosoma sp. |UniProt=Q9U6Y8 }} thumb|Bioluminescence response to local {{Chem|Ca|2+}} after intraperitoneal injection of recombinant tdTA in an anesthetized mouse. An overlay of the mouse reflection image (grayscale) and {{Chem|Ca|2+}}-induced bioluminescence (red pseudocolor) is shown. '''Red fluorescent protein''' ('''RFP''') is a protein which acts as a fluorophore, fluorescing red-orange when excited. The original variant occurs naturally in the coral genus ''Discosoma'', and is named '''DsRed'''. Several new variants have been developed using directed mutagenesis<ref name="Bevis">{{cite journal |last1=Bevis |first1=Brooke J. |last2=Glick |first2=Benjamin S. |date=2002 |title=Rapidly maturing variants of the Discosoma red fluorescent protein (DsRed) |journal=Nature Biotechnology |language=En |volume=20 |issue=1 |pages=83–87 |doi=10.1038/nbt0102-83 |issn=1546-1696 |pmid=11753367 |s2cid=20320166}}</ref> which fluoresce orange, red, and far-red.<ref>{{cite journal|last1=Miyawaki|first1=Atsushi|last2=Shcherbakova|first2=Daria M|last3=Verkhusha|first3=Vladislav V|title=Red fluorescent proteins: chromophore formation and cellular applications|journal=Current Opinion in Structural Biology|date=October 2012|volume=22|issue=5|pages=679–688|doi=10.1016/j.sbi.2012.09.002|pmid=23000031|pmc=3737244|issn=0959-440X}}</ref>
== Characteristics and properties == Like GFP and other fluorescent proteins, RFP is a barrel-shaped protein made primarily out of β-sheet motifs; this type of protein fold is commonly known as a β-barrel.
The mass of RFP is approximately 25.9 kDa. Its excitation maximum is 558 nm, and its emission maximum is 583 nm.<ref name="Remington">{{cite journal|last1=Remington|first1=S. James|title=Negotiating the speed bumps to fluorescence|journal=Nature Biotechnology|date=1 January 2002|volume=20|issue=1|pages=28–29|doi=10.1038/nbt0102-28|pmid=11753356|s2cid=37021603 |language=En}}</ref>
== Applications == RFP is frequently used in molecular biology research as a fluorescent marker, for a variety of purposes. DsRed has been shown to be more suitable for optical imaging approaches than EGFP.<ref name="pmid29890843">{{cite journal |vauthors=Böhm I, Gehrke S, Kleb B, Hungerbühler M, Müller R, Klose KJ, Alfke H |year=2019 |title=Monitoring of tumor burden in vivo by optical imaging in a xenograft SCID mouse model: evaluation of two fluorescent proteins of the GFP-superfamily |journal=Acta Radiol |volume=60 |issue=3 |pages=315–326 |doi=10.1177/0284185118780896 |pmid=29890843 |s2cid=48353442}}</ref>
Issues with fluorescent proteins include the length of time between protein synthesis and expression of fluorescence. DsRed has a maturation time of around 24 hours,<ref name="Bevis"/> which renders it unsuited for experiments that take place over a shorter time frame. Additionally, DsRed exists in a tetrameric form, which can affect the function of proteins to which it is attached. Genetic engineering has improved the utility of RFP by increasing the speed of fluorescence development and creating monomeric variants.<ref name="Remington"/><ref name="Piat">{{cite journal |last1=Piatkevich |first1=Kiryl D. |last2=Verkhusha |first2=Vladislav V. |date=2011 |title=Guide to Red Fluorescent Proteins and Biosensors for Flow Cytometry |journal=Methods in Cell Biology |volume=102 |pages=431–461 |doi=10.1016/B978-0-12-374912-3.00017-1 |isbn=9780123749123 |issn=0091-679X |pmc=3987785 |pmid=21704849}}</ref> Improved variants of RFP include the mFruits variants (mCherry, mOrange, mRaspberry), mKO, TagRFP, mKate, mRuby, FusionRed, ''mScarlet'' and DsRed-Express.<ref name="Piat" /><ref>{{cite journal|last1=Bindels|first1=Daphne S|last2=Haarbosch|first2=Lindsay|title=mScarlet: a bright monomeric red fluorescent protein for cellular imaging|journal=Nature Methods|date=2017|volume=14|issue=1|pages=53–56|doi=10.1038/nmeth.4074|pmid=27869816|s2cid=3539874 |language=En|issn=1548-7105}}</ref>
In contrast to many engineered monomeric red fluorescent proteins, tdTomato is derived from DsRed through directed evolution and is characterized by low acid sensitivity. Originating from ''Discosoma'' species, tdTomato is reported to be six times brighter than enhanced green fluorescent protein (EGFP), with excitation and emission peaks at 554 nm and 581 nm, respectively <ref>Chishti, A. A., Hellweg, C. E., Berger, T., Baumstark-Khan, C., Feles, S., Kätzel, T., & Reitz, G. (2015). Constitutive expression of tdTomato protein as a cytotoxicity and proliferation marker for space radiation biology. Life Sciences in Space Research, 4, 35–45. https://doi.org/10.1016/j.lssr.2014.12.005</ref>. Although it is a tandem dimer, tdTomato behaves as a functional monomer in fusion constructs. It is commonly used as an endoplasmic reticulum (ER) marker in various plant species for both transient and stable expression, and as a reporter gene to monitor gene expression, protein localization, and cell behavior <ref>Nagano, M., Ueda, H., Yoichiro Fukao, Maki Kawai-Yamada, & Ikuko Hara-Nishimura. (2020). Generation of Arabidopsis lines with a red fluorescent marker for endoplasmic reticulum using a tail-anchored protein cytochrome b5-B. Plant Signaling & Behavior, 15(9), 1790196–1790196. https://doi.org/10.1080/15592324.2020.1790196</ref>.
== Other fluorescent proteins == The first fluorescent protein to be discovered, green fluorescent protein (GFP), has been adapted to identify and develop fluorescent markers in other colors. Variants such as yellow fluorescent protein (YFP) and cyan fluorescent protein (CFP) were discovered in Anthozoa.<ref name="Piat"/>
== See also == * Cyan fluorescent protein (CFP) * Green fluorescent protein (GFP) * Yellow fluorescent protein (YFP)
== References == {{reflist}}
== External links == * [https://www.fpbase.org/protein/dsred/ DsRed] on FPBase
Category:Fluorescent proteins