FluoTag®-X2 anti-ALFA

Cat No: N1502 Category:


FluoTag®-X2 anti-ALFA is derived from an in-house developed single-domain antibody (sdAb) that recognizes a small rationally-designed epitope tag: the ALFA tag.

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FluoTag®-X2 anti-ALFA is derived from an in-house developed single-domain antibody (sdAb) that recognizes a small rationally-designed epitope tag: the ALFA tag. A full characterization of the system can be found in an open source article published in Nat. Commun. in 2019.

Our FluoTag-X2 series binds in a monovalent fashion with high affinity and specificity irrespective of whether the sample is alive or fixed with 4% paraformaldehyde, 2% glutaraldehyde, or methanol. Additionally, like all X2 FluoTags, it features two site-specifically coupled fluorophores per sdAb.

Owing to the small size of our FluoTags and the short ALFA-tag (15 amino acids; PSRLEEELRRRLTEP), the distance between the target epitope and each fluorophore is below 3 nm. Proteins of interest can be tagged with our ALFA-tag at the N-termini, C-termini, or in-between domains and they can also be immunoprecipitated or natively purified with complexes or partner binders using our series of ALFA-Selector resins with physiological elution capability.

Therefore, this ALFA tag and the companion FluoTags®-X2 anti-ALFA and ALFA-Selectors are the perfect choices for fluorescent-based experiments that want to be combined with biochemical purifications, mass-spectrometry, or any other high-end application.

FluoTags® can be equipped with a single fluorophore for more quantitative readouts (FluoTag®-Q), with two fluorophores per single-domain antibody (FluoTag®-X2), and we also developed a blend of two sdAbs bindings simultaneously the target proteins and each bearing two fluorophores (FluoTag®-X4). For more detailed information on the FluoTags, please check our Technology Section.

Conjugation Amount Cat No. RRID
Atto488 200 μl N1502-At488-L AB_3075982
AZDye568 200 μl N1502-AF568-L AB_3075980
Atto643 200 μl N1502-At643-L AB_3075983
Alexa647 200 μl N1502-AF647-L AB_3075981
LI-COR IRDye 680RD 200 μl N1502-Li680-L AB_3075984
LI-COR IRDye 800CW 200 μl N1502-Li800-L AB_3075985
AbberiorStar635P 200 μl N1502-Ab635P-L AB_3075979
Related Products: -
Clone: 1G5
Host: Alpaca
Produced in: E. coli
Application: IF, IHC, WB
Dilution: 1:500 (corresponding to 5 nM final concentration)
Capacity: N/A
Antigen: -
Targets: ALFA-tag
Specificity: It recognizes the ALFA tag (SRLEEELRRRLTE).
Formulation: The single sdAb clone was lyophilized from PBS pH 7.4, containing 2% BSA (US-Origin). Reconstitute with 200 µL of 50 % glycerol in deionized water. We recommend including 0.1 % sodium azide as a preservative if applicable. When reconstituted with 200 µl, the concentration of single-domain antibody is 2.5 µM
kDa: -
Ext Coef: -
Shipping: Ambient temperature
Storing: Vials containing lyophilized protein can be stored at 4 °C for 6 months. We recommend reconstituting the protein with 50 % sterile glycerol including 0.1 % sodium azide as preservative if applicable. Minimize the number of freeze-thaw cycles by aliquoting the reconstituted protein. Long term storage at -80 °C for up to 6 months. Working aliquots can be stored at -20 °C for up to 4 weeks. We do not recommend storing the reconstituted protein at 4 °C.

Look at detailed protocols in our Resource Section.


  1. Götzke H, Kilisch M, Martínez-Carranza M, Sograte-Idrissi S, Rajavel A, Schlichthaerle T, Engels N, Jungmann R, Stenmark P, Opazo F, Frey S. The ALFA-tag is a highly versatile tool for nanobody-based bioscience applications. Nat Commun. 2019 Sep 27;10(1):4403. doi: 10.1038/s41467-019-12301-7. PMID: 31562305; PMCID: PMC6764986.
  2. Neitthoffer B, Alvarez F, Larrous F, Caillet-Saguy C, Etienne-Manneville S, Boëda B. A short sequence in the tail of SARS-CoV-2 envelope protein controls accessibility of its PDZ-binding motif to the cytoplasm. J Biol Chem. 2024;300(1):105575. doi:10.1016/j.jbc.2023.105575 (IF; human HeLa)
  3. Westlund E, Bergenstråle A, Pokhrel A, et al. Application of nanotags and nanobodies for live cell single-molecule imaging of the Z-ring in Escherichia coli. Curr Genet. 2023;69(2-3):153-163. doi:10.1007/s00294-023-01266-2 (STED, PALM; E.coli)
  4. Zhang L, Stauffer WT, Wang JS, et al. Recruitment of Polo-like kinase couples synapsis to meiotic progression via inactivation of CHK-2. Elife. 2023;12:e84492. Published 2023 Jan 26. doi:10.7554/eLife.84492 (IF; C. elegans)
  5. Rudd-Schmidt JA, Laine RF, Noori T, Brennan AJ, Voskoboinik I. ALFA-PRF: a novel approach to detect murine perforin release from CTLs into the immune synapse. Front Immunol. 2022;13:931820. Published 2022 Dec 22. doi:10.3389/fimmu.2022.931820 (Live cell TIRF & Live cell spinning disk confocal imaging; mouse primary T cells)
  6. Igreja C, Loschko T, Schäfer A, et al. Application of ALFA-Tagging in the Nematode Model Organisms Caenorhabditis elegans and Pristionchus pacificus. Cells. 2022;11(23):3875. Published 2022 Dec 1. doi:10.3390/cells11233875 (IF; C. elegans, P. pacificus)
  7. Fessler E, Krumwiede L, Jae LT. DELE1 tracks perturbed protein import and processing in human mitochondria. Nat Commun. 2022;13(1):1853. Published 2022 Apr 6. doi:10.1038/s41467-022-29479-y (Flow Cytometry, WB; human HAP1)
  8. Akhuli D, Dhar A, Viji AS, Bhojappa B, Palani S. ALIBY: ALFA Nanobody-Based Toolkit for Imaging and Biochemistry in Yeast. mSphere. 2022;7(5):e0033322. doi:10.1128/msphere.00333-22 (IF; yeast)
  9. Rudolph M, Carsten A, Kulnik S, Aepfelbacher M, Wolters M. Live imaging of Yersinia translocon formation and immune recognition in host cells. PLoS Pathog. 2022;18(5):e1010251. Published 2022 May 23. doi:10.1371/journal.ppat.1010251  (IF, STED, life cell imaging; human HeLa infected with Y. enterocolitica)
  10. Frodyma DE, Troia TC, Rao C, et al. PGC-1β and ERRα Promote Glutamine Metabolism and Colorectal Cancer Survival via Transcriptional Upregulation of PCK2. Cancers (Basel). 2022;14(19):4879. Published 2022 Oct 5. doi:10.3390/cancers14194879 (IF, confocal microscopy; human colorectal cancer cell lines)
  11. Wiktor J, Gynnå AH, Leroy P, et al. RecA finds homologous DNA by reduced dimensionality search [published correction appears in Nature. 2021 Dec;600(7887):E11]. Nature. 2021;597(7876):426-429. doi:10.1038/s41586-021-03877-6 (STED)
  12. Zimmer MM, Kibe A, Rand U, et al. The short isoform of the host antiviral protein ZAP acts as an inhibitor of SARS-CoV-2 programmed ribosomal frameshifting. Nat Commun. 2021;12(1):7193. Published 2021 Dec 10. doi:10.1038/s41467-021-27431-0 (WB; human Huh7)
  13. Silbern I, Pan KT, Fiosins M, et al. Protein Phosphorylation in Depolarized Synaptosomes: Dissecting Primary Effects of Calcium from Synaptic Vesicle Cycling. Mol Cell Proteomics. 2021;20:100061. doi:10.1016/j.mcpro.2021.100061 (IF; rat)
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Notice: To be used in vitro/ for research only. Non-toxic, non-hazardous, non-infectious.
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