Myostatin Inhibitor / Activin-Binding Protein
Follistatin 344 (FST-344) Research Peptide
Follistatin 344 (FST-344) is a specific isoform of follistatin, an endogenous glycoprotein that acts as a potent antagonist of myostatin (GDF-8), activin A/B, and other members of the TGF-β superfamily. By binding and neutralizing these ligands, follistatin modulates skeletal muscle mass, folliculogenesis, and several developmental processes.
Compound identity
- Name
- Follistatin 344
- Class
- Myostatin Inhibitor / Activin-Binding Protein
- CAS number
- 80449-31-6
- Also known as
- FST-344, Follistatin, FS-344
- Sequence
- 288-aa isoform (Follistatin-344 splice variant, N-terminal secretory signal cleaved; MW ~35 kDa glycoprotein)
Research context
Follistatin (CAS 80449-31-6 for the follistatin protein) is an endogenous single-chain glycoprotein derived from the FST gene. Alternative splicing produces multiple isoforms; follistatin-344 refers to the 344-amino-acid precursor form, which — after cleavage of the 29-amino-acid N-terminal secretory signal — yields the mature 315-amino-acid circulating protein (FS-315), also designated follistatin-344 in many research contexts. The protein contains three structurally similar follistatin domains (FSD1, FSD2, FSD3) each with a cystine-rich core that mediates ligand binding. Follistatin binds myostatin (GDF-8), activin A, activin B, activin AB, GDF-11, and BMP-2/4/7 with high affinity, and the neutralized ligand complexes are cleared from circulation without receptor activation.
The research significance of follistatin centers on its role in skeletal muscle regulation. Myostatin (GDF-8) is a negative regulator of skeletal muscle mass — myostatin knockout mice develop approximately twice the muscle mass of wild-type mice, and naturally occurring myostatin-null mutations in cattle and humans produce pronounced muscle hypertrophy. Because follistatin neutralizes myostatin, research examining FST-344 has studied whether its administration can phenocopy myostatin deficiency. Preclinical studies in mice — including work by Lee, Zimmers, and colleagues — demonstrated significant muscle mass increases with follistatin overexpression or administration. Activin antagonism by follistatin is also studied in the context of cancer cachexia (where elevated activin A/B contribute to muscle wasting) and bone density research (BMP family regulation).
As a research reagent, follistatin 344 is used in skeletal muscle biology, myostatin pathway research, and TGF-β superfamily signaling studies. DMV Research supplies FST-344 as a lyophilized powder with per-batch third-party Certificate of Analysis confirming identity by mass spectrometry and purity by HPLC to 99%+.
Frequently asked questions
What is follistatin 344?+
Follistatin 344 (FST-344) is an isoform of follistatin, an endogenous glycoprotein that binds and neutralizes myostatin (GDF-8), activin A/B, and other TGF-β superfamily ligands. By antagonizing myostatin — a negative regulator of skeletal muscle mass — follistatin has been studied in preclinical models of muscle hypertrophy and muscle-wasting conditions.
How does follistatin 344 differ from follistatin 315?+
The numbering refers to isoform designation. The FST gene produces multiple splice variants; the 344-residue precursor (FS-344) is processed to a 315-residue circulating mature form (FS-315) after signal peptide cleavage. FS-315 has high heparan sulfate proteoglycan affinity, which tends to concentrate it at cell surfaces and limit its systemic circulation. FS-344 (the precursor form) is sometimes preferred in research for its slightly different tissue distribution profile. Both isoforms bind and neutralize myostatin, activin, and related ligands.
What is the difference between follistatin and myostatin inhibition?+
Myostatin inhibition can be achieved by several mechanisms: anti-myostatin antibodies (like stamulumab), myostatin propeptide, soluble ActRIIB (which blocks myostatin + activin signaling at the receptor level), or follistatin (which binds and sequesters myostatin + activin + BMPs). Follistatin is a broader-acting ligand trap compared to myostatin-specific antibodies, as it neutralizes multiple TGF-β family members.
Is follistatin 344 approved for human use?+
No. Follistatin is not FDA-approved for any indication. Gene therapy vectors expressing follistatin are in early clinical development for certain neuromuscular diseases, but the recombinant protein itself is not approved. As supplied by DMV Research, it is for in-vitro and pre-clinical laboratory research purposes only.
Research use only
All products are intended for laboratory and research use only (RUO) and are not for human consumption, ingestion, or any in-vivo use.
The statements on this page have not been evaluated by the FDA. Follistatin 344 is not intended to diagnose, treat, cure, or prevent any disease. Content is provided for laboratory research reference only.