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.

Amount Conjugation Cat No.
Atto488 200 μl N1502-At488-L
AZDye568 200 μl N1502-AF568-L
Atto643 200 μl N1502-At643-L
Alexa647 200 μl N1502-AF647-L
LI-COR IRDye 680RD 200 μl N1502-Li680-L
LI-COR IRDye 800CW 200 μl N1502-Li800-L
AbberiorStar635P 200 μl N1502-Ab635P-L
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.


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.
Notice: To be used in vitro/ for research only. Non-toxic, non-hazardous, non-infectious.
Legal terms: By purchasing this product you agree to our general terms and conditions.