Recombinant Human VEGFR1 (carrier-free)

Pricing & Availability
Regulatory Status
Other Names
Fms-related tyrosine kinase 1, oncogene FLT, FLT, FLT-1, VEGFR1, VEGFR-1, VEGFR
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Product Citations
Inhibition of HUVEC cell proliferation induced by VEGF165 in the presence of human soluble VEGFR1.
  • VEGFR1_Human_RECOM_BA_091014.jpg
    Inhibition of HUVEC cell proliferation induced by VEGF165 in the presence of human soluble VEGFR1.
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555802 10 µg 209 CHF
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555804 25 µg 440 CHF
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Cat. No. 555802 is scheduled for discontinuation. Please use the availability checker to determine current availability. The larger size is available as an alternative.

The VEGF family includes five members, VEGFA (VEGFA165), VEGFB, VEGFC, VEGFD and placenta growth factor (PLGF). Structurally, these growth factors are homodimers although heterodimers have been described that are composed of VEGFA and PLGF. There are three VEGF receptor tyrosine kinases: VEGFR1 (Flt1), VEGFR2 (Flk1), and VEGFR3 (Flt4). The expression of these receptors is overlapping; nevertheless, a distribution pattern has been reported: VEGFR1 is expressed on monocytes and macrophages, VEGFR2 on vascular endothelial cells, and VEGFR3 on lymphatic endothelial cells. VEGFR1 and VEGFR2 share 43.2% amino acid sequence homology and are structurally similar. VEGFR1 is an angiogenic and anti-angiogenic factor depending on the ligand binding it (PLGF-1 inhibits angiogenesis, whereas VEGF and PLGF2 are pro-angiogenic). Also, VEGFR1 mediates the angiostatic effect of pigment epithelium-derived factor (PEDF). A soluble form of VEGFR1 was initially identified in conditioned culture medium of HUVEC cells and it was found that it binds with high affinity to VEGFA. Soluble VEGFR1 and VEGFR2 act as decoy receptors for VEGFA, regulating the availability of VEGFA of which there are at least four different alternatively spliced soluble proteins. sVEGFR1 expression is upregulated by hypoxic conditions via HIF1-α in cytotrophoblasts. In preeclampsia activated platelets bind to monocytes to produce sVEGFR1. Increased circulating sVEGFR1 has been correlated with reduced free PLGF and reduced free VEGF in the blood compared to normal pregnancies. In addition, sVEGFR1 has been detected in cornea, and it is essential for preserving the avascular ambit of the cornea.

Product Details
Technical Data Sheet (pdf)

Product Details

Human VEGFR1, amino acids (Ser27-His687) (Accession# U01134), was expressed in 293E cells. An 8 His-tag is at the carboxyl terminal.
Molecular Mass
The 674 amino acid recombinant protein has a predicted molecular mass of approximately 76.2 kD. The DTT-reduced and non-reduced protein migrate at approximately 120 kD by SDS-PAGE. The predicted N-terminal amino acid is Ser.
>95%, as determined by Coomassie stained SDS-PAGE.
0.22 µm filtered protein solution is in 20 mM MOPS, 150 mM NaCl, 1 mM CHAPS pH 6.5.
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.
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.
ED50 = 20 - 100 ng/ml, corresponding to a specific activity of 1 - 5 x 104 units/mg, as determined by inhibition of HUVEC cell proliferation.


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

Product Citations
  1. Cheng J, et al. 2022. iScience. 25:103588. PubMed

Antigen Details

Cytokine receptor

Endothelial cells, placental trophoblast cells, peripheral blood monocytes and macrophages

VEGFR1 plays a key role in angiognesis and vasculogenesis. It is regulated by PEDF, which effects its intracellular proteolysis rate. sVEGFR1 regulates the availability of VEGFA and is produced in the placenta under hypoxic conditions.
Cell Type
Hematopoietic stem and progenitors, Mesenchymal Stem Cells, Neural Stem Cells
Biology Area
Angiogenesis, Cell Biology, Neuroscience, Stem Cells, Synaptic Biology
Molecular Family
Cytokine/Chemokine Receptors, Soluble Receptors
Antigen References

1. Kendall RL, et al. 1996. Biochem. Biophys. Res. Commun. 226:324.
2. Cai J, et al. 2006. J. Biol. Chem. 281:3604.
3. Ambati BK, et al. 2006. Nature 443:993.
4. Heydarian M, et al. 2009. Placenta 30:250.
5. Thomas CP, et al. 2009. J. Clin. Endocrinol. Metab. 94:2524. 
6. Wu, et al. 2010. J. Cell Mol. Med. 14:528.
7. Cai J, et al. 2011. PLoS One 6:e18076.

Gene ID
2321 View all products for this Gene ID
View information about VEGFR1 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) = 10e6/ ED50 (ng/mL)
Go To Top Version: 1    Revision Date: 09.24.2014

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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