Follistatin-315 is the shorter isoform of follistatin that circulates more freely and has broader tissue distribution than FS344. It binds and neutralizes myostatin, activin, and other TGF-beta superfamily ligands. It has a shorter half-life than FS344 due to less heparin binding.
Category: Muscle Growth / Research. Evidence rating: D (animal/preclinical only).
Clinical status: Research-only
FS315 binds myostatin with high affinity, preventing it from signaling through ActRIIB receptors. This removes the brake on muscle growth. It also sequesters activin A/B and inhibits other TGF-beta superfamily members involved in muscle wasting and fibrosis.
Safety considerations: Reproductive effects from activin suppression; Potential tumor promotion via TGF-beta inhibition; No human safety data for injectable form.
Reviewed by the PeptideAtlas Editorial Team.
| Production method | recombinant |
|---|---|
| Anti-doping status | Prohibited in sport (WADA) |
Related peptides: ACE-031.
FS344 has a longer C-terminal tail that binds heparan sulfate proteoglycans on cell surfaces, keeping it localized. FS315 lacks this tail, so it circulates freely with broader tissue distribution but shorter half-life.
Follistatin 315 is a tissue-bound isoform of follistatin with more localized myostatin-blocking activity compared to the circulating Follistatin 344 variant.
FOLLISTATIN 315 has been studied for: Localized myostatin inhibition, Targeted muscle support, Lean mass preservation. Tissue-bound follistatin isoform; more targeted than FS-344.
Binds activin and myostatin locally within muscle tissue due to heparin-binding domain, providing targeted inhibition rather than systemic effects.