Follistatin-344 (FST-344) 1mg

What is Follistatin-344?

Follistatin-344 is the full-length isoform of human follistatin, a secreted single-chain glycoprotein that binds activin with very high affinity and also neutralises myostatin (GDF-8) and several other TGF-beta superfamily ligands. The FST gene is alternatively spliced into two main isoforms: FST-344, the precursor to the circulating FST-315 form, and FST-317, the precursor to the tissue-bound FST-288 form.

The name refers to the 344-residue precursor, which includes a 29-residue signal peptide; the mature secreted protein is 315 amino acids. Follistatin-344 is the form most commonly supplied for research because it is soluble and circulates freely, while the shorter isoform binds cell-surface heparan sulfate and remains local. It is a recombinant protein, not a short synthetic peptide, so molecular weight depends on glycosylation and no single CAS number applies.

GenoPept supplies Follistatin-344 to UK laboratories as a 1mg lyophilised vial, independently verified at ≥99% purity with a batch Certificate of Analysis.

Follistatin-344 research applications

Follistatin-344 is used as a native antagonist of activin and myostatin in a range of preclinical research areas:

• Myostatin neutralisation – it is studied in myoblast cultures and animal models to block myostatin signalling and examine effects on muscle fibre size and satellite cells.
• Activin biology – as the endogenous activin-binding protein, follistatin is used in reproductive, pituitary and inflammation research to inhibit activin A and B.
• Gene-therapy models – FST-344 has been the transgene in preclinical and early clinical gene-transfer studies in the compound class, providing a reference for recombinant protein work.
• Fibrosis and tissue repair – activin drives fibrotic responses in liver, kidney and lung models, and follistatin is investigated as a counter-regulator.
• Stem cell and developmental studies – follistatin modulates activin and BMP gradients in embryonic and organoid systems.

Mechanism of action (preclinical)

Follistatin-344 binds activin dimers in a 2:1 complex that encircles the ligand and blocks both its type I and type II receptor-binding surfaces, preventing ActRIIA/ActRIIB engagement and downstream SMAD2/3 phosphorylation. It binds myostatin and GDF-11 through the same follistatin domains, though with lower affinity than activin.

By removing the myostatin and activin brake on muscle progenitors, follistatin is reported in preclinical models to increase muscle mass. Its heparin-binding sequence also allows the FST-288 form to localise ligands to the cell surface, while FST-315 derived from FST-344 acts systemically.

Follistatin-344 product specifications

Each vial is supplied to the specification below. Rows are limited to values that can be verified from published sources.

Available sizes

• Follistatin-344 1mg vial, lyophilised powder

Bulk and wholesale boxes of 10 vials of Follistatin-344 save 20–50% for laboratories running larger studies; see the bulk and wholesale page. Free UK delivery applies to orders of £200 or more.

Reconstitution, handling and storage (laboratory)

Follistatin-344 is shipped as a lyophilised powder and should be stored unopened at –20 °C for long-term laboratory storage, or at 2–8 °C for short periods, protected from light. Allow the sealed vial to reach room temperature before opening to avoid condensation on the powder.

To reconstitute, add bacteriostatic water or another sterile diluent slowly down the inside wall of the vial, then swirl gently until dissolved. Never shake, as shear stress can denature the peptide. Follistatin-344 is a glycosylated protein sensitive to shear and surface adsorption, so use low-binding labware and avoid repeated freeze–thaw cycles. After reconstitution keep the solution at 2–8 °C and use it within the period defined in your laboratory protocol.

Full step-by-step guidance is available in our articles on how to reconstitute research peptides and how to store research peptides. Handle with gloves and standard laboratory precautions.

Quality assurance and Certificate of Analysis

Every batch of Follistatin-344 is tested by an independent third-party laboratory (Puralytix, ISO/IEC 17025 accredited). Purity is confirmed by HPLC at ≥99% and identity is confirmed by LC-MS, so the material in the vial matches the label.

A batch-specific Certificate of Analysis is available through the “View Certificate of Analysis” button on this page, and the complete library is published in the COA library. Our guide to what a Certificate of Analysis shows explains how to read the chromatogram and mass spectrum. Vials are batch-identified with lot number and expiry, and orders are dispatched discreetly by tracked Royal Mail Special Delivery within the UK.

Related research compounds

• GDF-8 (Myostatin) 1mg – the ligand that follistatin neutralises, for binding and bioassay work
• ACE-031 1mg – an engineered ActRIIB-Fc decoy receptor for comparative ligand-trap studies
• IGF-1 LR3 – anabolic IGF-1 signalling studied alongside myostatin inhibition
• MGF 2mg – IGF-1Ec E-domain peptide for muscle progenitor research

Follistatin-344 frequently asked questions

What is Follistatin-344 used for in research?

Follistatin-344 is used in laboratory research as a natural antagonist of activin and myostatin. Applications include neutralising myostatin in myoblast cultures and animal models, studying activin signalling in reproductive and inflammatory systems, fibrosis models, developmental biology and comparisons with engineered ligand traps such as ACE-031. Supplied for in-vitro laboratory research only.

How is Follistatin-344 supplied and what is its purity?

GenoPept supplies Follistatin-344 as 1mg of lyophilised recombinant protein in a sealed, sterile glass vial with a black cap and batch label. Each lot is tested by an independent ISO/IEC 17025 laboratory, with ≥99% purity by HPLC and identity confirmed by LC-MS. The batch Certificate of Analysis is available on the product page.

How should Follistatin-344 be stored?

Store unopened Follistatin-344 vials at –20 °C for long-term storage or at 2–8 °C for short periods, protected from light. After reconstitution keep the solution at 2–8 °C, use low-protein-binding tubes, avoid freeze–thaw cycles and use within the period defined by your laboratory protocol.

Is Follistatin-344 for human use?

No. Follistatin-344 is supplied strictly for in-vitro laboratory research. It is not a medicine, is not approved for human or veterinary use and is not for diagnostic or therapeutic purposes. UK customers must accept the research use only policy before an order is processed.

What is the difference between Follistatin-344 and Follistatin-315?

FST-344 is the full-length precursor isoform including its signal peptide; once secreted and processed it becomes the 315-amino-acid circulating form, FST-315. Recombinant products labelled Follistatin-344 therefore correspond to this soluble, systemic isoform. The alternative splice form, FST-317, yields FST-288, which binds heparan sulfate and acts locally at the cell surface.

Research use only. This product is supplied strictly for in-vitro laboratory research. It is not for human or veterinary use, not a medicine, and not for diagnostic or therapeutic use. Read the GenoPept research use only policy before ordering.