- Other Names
- Activin-Binding Protein, FST, FS
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- Product Citations
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Follistatin was initially isolated from porcine follicular fluid. Follistatin is a single chain glycoprotein that inhibits the secretion of FSH from the pituitary. Follistatin is a TGF-β family member antagonist, which along with other antagonists (noggin, chordin, DAN/Cerberus), binds to the ligands and interfere with their binding to the receptors. Follistatin binds to Activin with high affinity (Kd ∼45 pM), but it also binds other ligands with lower affinity, these additional ligands include: BMPs 2, 4, 6, 7, 11, and 15, and myostatin. It is known that follistatin knockout mice display defects in skeleton and muscle development size; therefore, they die shortly after birth. Follistatin is expressed in the ovary, kidney, and brain. In the ovary, follistatin mRNA expression is low in primordial follicles, but increases in the granulosa cells in secondary and tertiary follicles. Also, follistatin is produced by the liver and it seems to be the major source of follistatin in human serum. Changes in follistatin and activin expression have been associated with hepatic diseases such as inflammation, fibrosis, liver failure, and hepatocellular carcinoma.Product Details
- Mouse Follistatin amino acids (Gly30-Trp344) (Accession # P47931) was expressed in CHO cells The carboxy terminus contains 6His tag.
- Molecular Mass
- The 323 amino acid recombinant protein has a predicted molecular mass of approximately 35.6 kD. The DTT-reduced and non-reduced protein migrate at approximately 35 – 45 kD by SDS-PAGE. The predicted N-terminal amino acid is Gly.
- >95%, as determined by Coomassie stained SDS-PAGE.
- 0.22 μm filtered protein solution is in PBS pH7.2.
- Endotoxin Level
- Less than 0.10 EU per µg cytokine as determined by the LAL method.
- 10 and 25 µg sizes are bottled at 200 µg/mL. 100 µg and larger sizes are lot-specific and bottled at the concentration indicated on the vial (please contact technical support for concentration, or use our Lookup tool if you have a lot number.)
- 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.
- Mouse follistatin inhibits the inhibitory effect of recombinant human Activin A (Cat. No. 592002, at 30 ng/mL) in the proliferation of MPC-11 cells. The ED50 for this effect is 0.03 – 0.15 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 email@example.com.
Proliferating chondrocytes, osteoblasts, granulosa cells, intestinal epithelial cells.
- Inhibits follicle-stimulating hormone release, stimulate progesterone production from granulosa cells. Down-regulated by BMPs and induced by TGF-β.
- Activin A, BMPs 2, 4, 6, 7, 11, and 15, and myostatin.
- Molecular Family
- Enzymes and Regulators
- Antigen References
- Shimasaki S, et al. 1989. Mol Endocrinol. 3:651.
- Canalis E, et al. 2003. Endocr Rev. 24:218.
- Thompson TB, et al. 2005. Dev Cell. 9:535.
- Hansen JS, et al. 2016. J Clin Endocrinol Metab. 101:550.
- Polyzos SA, et al. 2016. Metabolism. 65:1550.
- Gene ID
- 14313 View all products for this Gene ID
- View information about Follistatin on UniProt.org
- 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.
- 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.
- 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)
- 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.