# LifeAct > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/LifeAct > Markdown URL: https://mediated.wiki/source/LifeAct.md > Source: https://en.wikipedia.org/wiki/LifeAct > Source revision: 1333090065 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) '''LifeAct''' is a 17 [amino acid](/source/amino_acid) recombinant peptide that stains filamentous [actin](/source/actin) (F-actin) structures of [eukaryotic](/source/eukaryotic) living or fixed cells.{{cite journal | vauthors = Riedl J, Crevenna AH, Kessenbrock K, Yu JH, Neukirchen D, Bista M, Bradke F, Jenne D, Holak TA, Werb Z, Sixt M, Wedlich-Soldner R | title = Lifeact: a versatile marker to visualize F-actin | journal = Nature Methods | volume = 5 | issue = 7 | pages = 605–7 | date = July 2008 | pmid = 18536722 | pmc = 2814344 | doi = 10.1038/nmeth.1220 }} There are several types and combinations of LifeAct that can be utilized depending on the cell type, protocol, and purpose of the analysis. == Lifeact amino acid sequence == Lifeact 17 [amino acid](/source/amino_acid) sequence is MGVADLIKKFESISKEE. == Types == * LifeAct Plasmid * LifeAct mRNA * LifeAct Adenovirus * LifeAct Lentivirus * LifeAct Protein == Chemistry == LifeAct-TagGFP2 being the most widely used fluorescent variant compared to other LifeAct constructs is composed of the first 17 amino acid from the ''[Saccharomyces cerevisiae](/source/Saccharomyces_cerevisiae)'' Abp140, an actin-binding protein. The Abp140 is highly conserved among ''Saccharomyces cerevisiae'' and other closely related organisms.{{cite journal | vauthors = Noma A, Yi S, Katoh T, Takai Y, Suzuki T, Suzuki T | title = Actin-binding protein ABP140 is a methyltransferase for 3-methylcytidine at position 32 of tRNAs in Saccharomyces cerevisiae | journal = RNA | volume = 17 | issue = 6 | pages = 1111–9 | date = June 2011 | pmid = 21518805 | pmc = 3096043 | doi = 10.1261/rna.2653411 }} The 17 amino acid fragment of Abp140 was genetically fused to GFP and fluoresces green when it binds the F-actin structures of living and fixed cells, allowing for visualization of cell mechanics under microscopes. Previous experiments involving the analysis of cell mechanics had depended on fluorescently labeled [phalloidin](/source/phalloidin) and actin GFP fusion proteins obtained from [utrophin](/source/utrophin) in ''[Xenopus laevis](/source/Xenopus_laevis)'' and ABP120 in ''[Dictyostelium discoideum](/source/Dictyostelium_discoideum)''.{{Cite web|url=https://www.cytoskeleton.com/actin-staining-techniques|title=Actin Staining Techniques - Actin staining protocols, Actin stain, Actin probe, Acti-stain 488 phalloidin, Acti-stain 555 phalloidin, Acti-stain 535 phalloidin, Acti-stain 670 phalloidin, Actin stain, Actin -stain488.|website=www.cytoskeleton.com |access-date=2018-09-05}}{{cite journal | vauthors = Hsu ST, Cabrita LD, Fucini P, Dobson CM, Christodoulou J | title = Structure, dynamics and folding of an immunoglobulin domain of the gelation factor (ABP-120) from Dictyostelium discoideum | journal = Journal of Molecular Biology | volume = 388 | issue = 4 | pages = 865–79 | date = May 2009 | pmid = 19281823 | doi = 10.1016/j.jmb.2009.02.063 }} However, due to their large protein size, markers such as [phalloidin](/source/phalloidin) and [GFP fusion protein](/source/GFP_fusion_protein)s are limited to cells that can be transfected and tend to compete with their [orthologous](/source/orthologous) protein. These localization markers affect cellular mechanical properties and F-actin structures, thus making these markers unreliable.{{cite journal | vauthors = Sliogeryte K, Thorpe SD, Wang Z, Thompson CL, Gavara N, Knight MM | title = Differential effects of LifeAct-GFP and actin-GFP on cell mechanics assessed using micropipette aspiration | journal = Journal of Biomechanics | volume = 49 | issue = 2 | pages = 310–7 | date = January 2016 | pmid = 26792287 | pmc = 4769141 | doi = 10.1016/j.jbiomech.2015.12.034 }} An alternative to these markers is Life Act-TagGFP2, which is a much smaller protein and does not affect cell mechanics. Cells synthesize LifeAct-TagGFP2 in a short period of time making it suitable as a cost-effective ''in vivo'' marker. == Applications in biomedical research == LifeAct peptides have been used as a universal marker for F-actin visualization in biomedical research. An experiment conducted by Sawant et al. utilized LifeAct GFP to visualize the migration of control [border cells](/source/Border_cells_(Drosophila)) in the ovaries of ''[Drosophila](/source/Drosophila)'' flies, in order to determine how cells move in terms of small and large collectives during development and cancer.{{cite journal | vauthors = Sawant K, Chen Y, Kotian N, Preuss KM, McDonald JA | title = Rap1 GTPase promotes coordinated collective cell migration in vivo | journal = Molecular Biology of the Cell | pages = mbcE17120752 | date = August 2018 | pmid = 30156466 | doi = 10.1091/mbc.E17-12-0752 | volume=29 | pmc=6249841}} Lifeact labels F-actin in border cells and adjacent [follicle cell](/source/follicle_cell)s allowed for the detailed examination of border [cell membrane](/source/cell_membrane)s and protrusions. Studies regarding the degradation of actin [cytoskeleton](/source/cytoskeleton) due to aging relied on LifeAct for the analysis of cytoskeletal organization as a function of age. [Transgenic](/source/Transgenic) lines that expressed the LifeAct in various tissues of ''C. elegans'' were primarily used for imaging.{{cite journal | vauthors = Higuchi-Sanabria R, Paul JW, Durieux J, Benitez C, Frankino PA, Tronnes SU, Garcia G, Daniele JR, Monshietehadi S, Dillin A | title = Spatial regulation of the actin cytoskeleton by HSF-1 during aging | journal = Molecular Biology of the Cell | pages = mbcE18060362 | date = August 2018 | pmid = 30133343 | doi = 10.1091/mbc.E18-06-0362 | volume=29 | pmc=6254583}} == References == {{Reflist}} Category:Protein imaging --- Adapted from the Wikipedia article [LifeAct](https://en.wikipedia.org/wiki/LifeAct) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/LifeAct?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.