Recombinant Human FGF-21 (carrier-free)

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Regulatory Status
Other Names
Fibroblast growth factor 21, FGF21
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Product Citations
Recombinant human FGFR4-Fc (Cat. No. 752502) binds to immobilized recombinant human FGF-21 in a dose-dependent manner. The ED50 for this effect is 0.04 – 0.2 µg/mL.
  • Human_FGF-21_CF_RECOM_1_081921
    Recombinant human FGFR4-Fc (Cat. No. 752502) binds to immobilized recombinant human FGF-21 in a dose-dependent manner. The ED50 for this effect is 0.04 – 0.2 µg/mL.
  • Human_FGF-21_CF_RECOM_2_081921
    Human FGF-21 induces NIH3T3 proliferation in the presence of recombinant mouse klotho beta and heparin, in a dose-dependent manner. BioLegend’s human FGF-21 product was compared side-by-side to a leading competitor’s equivalent product.
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553804 25 µg 223 CHF
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FGF-21 is an atypical member of the FGF superfamily and functions as an endocrine hormone. It is mainly secreted by the liver but also by other tissues including adipocytes, pancreas, and skeletal muscle. It can act not only locally but also can travel through the circulatory system and function as an endocrine hormone. FGF-21 signals through a complex formed by classic FGF receptors and the coreceptor β-Klotho. Although it has been shown that FGF-21 can bind all FGFR isotypes, in vitro studies have shown that FGF-21 prefers FGFR1c/β-Klotho complex. Since the expression of β-Klotho is restricted to several tissues including liver, adipose tissues, pancreas, CNS and testes, it is believed that these tissues are the major sites of FGF-21 action. In liver, FGF-21 can induce gluconeogenesis, fatty acid oxidation, triglyceride degradation, and ketogenesis. It has also been reported that PGC-1α, a key regulator of mitochondrial energy metabolism, can be induced by FGF-21. In adipose tissue, FGF-21 regulates lipolysis and stimulates glucose uptake independent of insulin. In pancreatic islets, FGF-21 can increase insulin expression. Transgenic mice overexpressing FGF-21 are protected from diet-induced obesity; therefore, FGF-21 has been considered a promising potential therapy for the treatment of obesity-related disorders. FGF-21 can cross the blood-brain barrier and FGF-21 has been shown to regulate peripheral metabolism and circadian behavior by acting on the nervous system. 

Product Details
Technical Data Sheet (pdf)

Product Details

Human FGF-21, amino acids His29-Ser209 (Accession# NP_061986) with an N-terminal Met and 5-His tag, was expressed in E. coli.
Molecular Mass
The 187 amino acid recombinant protein has a predicted molecular mass of approximately 20 kD. The DTT-reduced and non-reduced protein migrate at approximately 20 kD by SDS-PAGE. The predicted N-terminal amino acid is Met.
>95%, as determined by Coomassie stained SDS-PAGE.
0.22 µm filtered protein solution is in PBS.
Endotoxin Level
Less than 0.01 ng per µg cytokine as determined by the LAL method.
10 and 25 µg sizes are bottled at 200 µg/mL. 100 µg size and larger sizes are lot-specific and bottled at the concentration indicated on the vial. To obtain lot-specific concentration and expiration, please enter the lot number in our Certificate of Analysis online tool.
Storage & Handling
Unopened vial can be stored between 2°C and 8°C for up to 2 weeks, at -20°C for up to six months, or at -70°C or colder until the expiration date. For maximum results, quick spin vial prior to opening. The protein can be aliquoted and stored at -20°C or colder. Stock solutions can also be prepared at 50 - 100 µg/mL in appropriate sterile buffer, carrier protein such as 0.2 - 1% BSA or HSA can be added when preparing the stock solution. Aliquots can be stored between 2°C and 8°C for up to one week and stored at -20°C or colder for up to 3 months. Avoid repeated freeze/thaw cycles.
Recombinant human FGFR4-Fc (Cat. No. 752502) binds to immobilized recombinant human FGF-21 in a dose-dependent manner. The ED50 for this effect is 0.04 – 0.2 µg/mL.


Application Notes

BioLegend carrier-free recombinant proteins provided in liquid format are shipped on blue-ice. Our comparison testing data indicates that when handled and stored as recommended, the liquid format has equal or better stability and shelf-life compared to commercially available lyophilized proteins after reconstitution. Our liquid proteins are verified in-house to maintain activity after shipping on blue ice and are backed by our 100% satisfaction guarantee. If you have any concerns, contact us at

Antigen Details

Growth factor

Liver, adipose tissue, pancreas, and muscle.

FGF-21 is an important regulator of glucose and lipid metabolism. FGF-21 expression is regulated by PPARα and PPARγ in liver and adipose tissues respectively. Expression of FGF-21 is regulated by insulin/Akt in muscle tissue.
Cell Type
Embryonic Stem Cells, Hematopoietic stem and progenitors, Mesenchymal Stem Cells, Neural Stem Cells
Biology Area
Cell Biology, Neuroscience, Stem Cells, Synaptic Biology
Molecular Family
Cytokines/Chemokines, Growth Factors
Antigen References

1. Nishimura T, et al. 2000. Biochim Biophys Acta. 1492:203.
2. Kharitonenkov, et al. 2013. Mol. Metab. 3:221.
3. Luo Y, et al. 2013. Front. Endocrinol. 4:194.
4. Cheung BM, et al. 2014. Expert Rev. Cardiovasc.
5. Kharitonenkov A, et al. 2008. J. Cell Physiol. 215:1.
6. Bookout AL, et al. 2013. Nat. Med. 9:1147.
7. Potthoff, et al. 2009. Proc. Natl. Acad. Sci. 106:10853.

Gene ID
26291 View all products for this Gene ID
View information about FGF-21 on

Related FAQs

Why choose BioLegend recombinant proteins?

     • Each lot of product is quality-tested for bioactivity as indicated on the data sheet.
     • Greater than 95% Purity or higher, tested on every lot of product.
     • 100% Satisfaction Guarantee for quality performance, stability, and consistency.
     • Ready-to-use liquid format saves time and reduces challenges associated with reconstitution.
     • Bulk and customization available. Contact us.
     • Learn more about our Recombinant Proteins.

How does the activity of your recombinant proteins compare to competitors?

We quality control each and every lot of recombinant protein. Not only do we check its bioactivity, but we also compare it against other commercially available recombinant proteins. We make sure each recombinant protein’s activity is at least as good as or better than the competition’s. In order to provide you with the best possible product, we ensure that our testing process is rigorous and thorough. If you’re curious and eager to make the switch to BioLegend recombinants, contact your sales representative today!

What is the specific activity or ED50 of my recombinant protein?

The specific activity range of the protein is indicated on the product datasheets. Because the exact activity values on a per unit basis can largely fluctuate depending on a number of factors, including the nature of the assay, cell density, age of cells/passage number, culture media used, and end user technique, the specific activity is best defined as a range and we guarantee the specific activity of all our lots will be within the range indicated on the datasheet. Please note this only applies to recombinants labeled for use in bioassays. ELISA standard recombinant proteins are not recommended for bioassay usage as they are not tested for these applications.

Have your recombinants been tested for stability?

Our testing shows that the recombinant proteins are able to withstand room temperature for a week without losing activity. In addition the recombinant proteins were also found to withstand four cycles of freeze and thaw without losing activity.

Does specific activity of a recombinant protein vary between lots?

Specific activity will vary for each lot and for the type of experiment that is done to validate it, but all passed lots will have activity within the established ED50 range for the product and we guarantee that our products will have lot-to-lot consistency. Please conduct an experiment-specific validation to find the optimal ED50 for your system.

How do you convert activity as an ED50 in ng/ml to a specific activity in Units/mg?

Use formula Specific activity (Units/mg) = 10^6/ ED50 (ng/mL)

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For research use only. Not for diagnostic use. Not for resale. BioLegend will not be held responsible for patent infringement or other violations that may occur with the use of our products.


*These products may be covered by one or more Limited Use Label Licenses (see the BioLegend Catalog or our website, BioLegend products may not be transferred to third parties, resold, modified for resale, or used to manufacture commercial products, reverse engineer functionally similar materials, or to provide a service to third parties without written approval of BioLegend. By use of these products you accept the terms and conditions of all applicable Limited Use Label Licenses. Unless otherwise indicated, these products are for research use only and are not intended for human or animal diagnostic, therapeutic or commercial use.


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