- ≥98% by HPLC
- Lot-matched certificate of analysis
- Ships next business day, tracked
Follistatin-344
Recombinant 344-residue activin-binding glycoprotein isoform
- FormLyophilized recombinant protein, sealed glass vial
- Mol. weight37800 Da (approximately 37.8 kDa)
- Research areasMyostatin inhibition, skeletal-muscle mass regulation, follicular and reproductive biology, fibrosis models
Overview
Follistatin-344 is the recombinant 344-amino-acid isoform of follistatin, an autocrine glycoprotein first isolated from ovarian follicular fluid. Follistatin's defining property is high-affinity binding to members of the TGF-β superfamily — chiefly activin A, but also myostatin (GDF-8) and several bone morphogenetic proteins. By sequestering these ligands before they can engage their receptors, follistatin acts as a natural extracellular antagonist of that signalling axis.
Two principal isoforms arise from alternative splicing: FS-288, which carries a heparin-binding C-terminus and stays largely cell-associated, and FS-315, which circulates. FS-344 is the precursor form from which FS-315 is produced after signal-peptide processing, and it is the isoform most commonly expressed recombinantly for laboratory work. Because myostatin is a negative regulator of skeletal muscle mass, follistatin has been a persistent subject in muscle-biology and gene-transfer research since the 1990s.
Specifications
Identity
- CAS number
- 80449-31-6
- Molecular weight
- 37800 Da (approximately 37.8 kDa)
Supply & purity
- Form
- Lyophilized recombinant protein, sealed glass vial
- Purity
- ≥98% by HPLC; lot-matched COA available
- Available sizes
- 1 mg
- Solubility
- Sterile or bacteriostatic water; carrier protein often added for dilute stocks
Handling & storage
- Storage (lyophilized)
- −20 °C, protected from light and moisture
- Storage (reconstituted)
- 2–8 °C for immediate work; aliquot and hold at −20 °C or below for longer studies
Additional detail
- Residue count
- 344 amino acids
- Protein class
- Activin-binding glycoprotein, TGF-β superfamily antagonist
- Principal binding partners
- Activin A, myostatin (GDF-8), selected BMPs
- Isoform relationship
- Precursor isoform to circulating FS-315; distinct from cell-associated FS-288
- Research areas
- Myostatin inhibition, skeletal-muscle mass regulation, follicular and reproductive biology, fibrosis models
Working out the concentration
Because Follistatin-344 arrives dry, its concentration is a decision rather than a specification. Run the numbers through the reconstitution calculator — vial mass in, diluent volume in, mg/mL and mass per syringe unit out.
If the protocol asks for a molar concentration, the molar concentration calculator converts between 37800 Da (approximately 37.8 kDa), the mass you weigh out and the volume you dissolve it in.
Certificate of analysis
Every lot of Follistatin-344 is released against a certificate of analysis: the batch-specific laboratory data for that lot, not a generic document for the compound. The lot number on the certificate matches the lot number printed on the label you receive — the vial label itself, where the product is vialled — so the record and the material it describes can always be reconciled.
Purity: ≥98% by HPLC — the specification for this listing. The figure for the lot you receive is the one reported on that lot’s certificate.
No lot certificate is on display on this page at the moment. That is a publishing state and not a testing one: lots are released and documented as described above whether or not the document is posted here, and we will send what exists for the lot in stock, or for a lot already on your bench, by its number.
Certificates are available on request before you order as well as after, with no account and no charge. Request the certificate for this listing, read the testing and documentation policy in full, or see how to read a peptide COA.
Questions about Follistatin-344
What is Follistatin-344 and how does it differ from FS-288 and FS-315?
FS-344 is the 344-residue precursor isoform of follistatin. After signal-peptide processing it yields FS-315, the circulating form, while FS-288 is a shorter heparin-binding variant that stays cell-associated. The isoforms share the activin-binding core but differ in tissue distribution and handling.
Why is Follistatin-344 more expensive than most peptides?
It is a 344-residue recombinant glycoprotein of roughly 37.8 kDa, not a short synthetic peptide. Production requires expression in a biological system followed by multi-step purification and analysis, which is substantially more involved than solid-phase peptide synthesis.
Is the product third-party tested and is a COA available?
Yes. Each lot is analysed by an independent laboratory for purity and identity, and the certificate of analysis is matched to the lot number printed on your vial. You can request it before ordering or after the vial arrives.
How should Follistatin-344 be stored and reconstituted?
Keep the sealed lyophilized vial at −20 °C, protected from light and moisture. Reconstitute gently with sterile water without shaking, aliquot into single-use volumes, and avoid repeated freeze–thaw cycles, which degrade recombinant proteins of this size faster than small peptides.
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