ACE-031 vs Follistatin 344
ACE-031 (Myostatin-pathway inhibitor) and Follistatin 344 (Myostatin-pathway inhibitor) are documented as co-studied in the PeptiDex library. This page puts the two entries side by side on class, molecular weight, half-life, origin, mechanism and studied research areas — every value taken from the entry it belongs to.
Why these two are co-studied
Cross-referenced for research context — not a usage or combination recommendation.
At a glance
| Attribute | ACE-031 | Follistatin 344 |
|---|---|---|
| Compound class | Myostatin-pathway inhibitor | Myostatin-pathway inhibitor |
| Research category | Specialty & Research | Specialty & Research |
| Length (amino acids) | 343 amino acids | 344 amino acids |
| Molecular weight | ~80 kDa (glycosylated ActRIIB-Fc homodimer) | ~37,800 Da (mature glycoprotein isoform) |
| Half-life | Long (Fc-fusion protein; days-to-weeks range typical of IgG1-Fc biologics) | Not documented |
| Origin | ACE-031 (ramatercept) is an engineered soluble fusion protein consisting of a portion of the activin receptor type IIB (ActRIIB) extracellular domain fused to a human IgG Fc region. It was developed by Acceleron Pharma as an investigational myostatin-pathway agent. | Follistatin 344 (FST-344) is one of the naturally occurring isoforms of follistatin, an endogenous glycoprotein that binds and neutralizes members of the TGF-beta superfamily. It is studied as a research protein in the myostatin/activin pathway. |
“Not documented” means the PeptiDex entry records no value for that field. Nothing on this page is estimated, and no figure is carried over from one compound to the other.
How ACE-031 works
ACE-031 acts as a decoy receptor: its ActRIIB extracellular domain binds and sequesters ligands that normally signal through ActRIIB, including myostatin (GDF-8) and related TGF-beta superfamily members such as activins. By preventing these ligands from engaging cell-surface ActRIIB, it blocks the negative regulatory signaling that restrains muscle growth, which in studies was associated with increased muscle mass. It is a fusion protein rather than a small peptide.
How Follistatin 344 works
Follistatin is a secreted protein that binds with high affinity to activin and to myostatin (GDF-8), neutralizing these ligands and preventing them from activating activin type II receptors. By sequestering myostatin, follistatin removes a negative regulator of skeletal muscle growth, which in animal studies is associated with increased muscle mass. The 344 isoform includes an N-terminal signal/acidic region and is processed to shorter forms such as FST-315 and FST-288 with differing tissue-binding properties.
Mechanistic descriptions reflect published research-literature understanding and are quoted from each compound's own entry. Much peptide research is preclinical (in-vitro or animal-model); mechanism in humans may differ and is not established for many compounds.
Where each one appears in the literature
The research contexts each entry documents. Listing a research area is not a claim of efficacy or a therapeutic indication, and the two lists are not scored against each other.
ACE-031
Follistatin 344
What sets each apart
ACE-031
ACE-031 is a soluble ActRIIB-Fc decoy receptor that traps multiple ligands at the receptor level, differing from Follistatin, which binds myostatin/activin as a natural extracellular antagonist.
Follistatin 344
Follistatin-344 is a natural ligand-binding antagonist of myostatin/activin, distinct from ACE-031, which is an engineered ActRIIB-Fc decoy receptor acting at the receptor.
Frequently asked questions
What is ACE-031 and what class of molecule is it?
ACE-031 (also called ramatercept) is not a small peptide but a recombinant fusion protein: the extracellular domain of the human activin receptor type IIB (ActRIIB / ACVR2B) fused to the Fc portion of human IgG1. It functions as a soluble 'ligand trap' or decoy receptor. Its class is a myostatin/activin-pathway inhibitor.
How does ACE-031 work as a myostatin inhibitor?
As a soluble decoy receptor it circulates and binds TGF-beta superfamily ligands - most notably myostatin (GDF-8), but also activin A/B, GDF-11 and certain BMPs - before they can engage native membrane-bound ActRIIB. By sequestering these growth-inhibitory ligands, it is studied for effects on muscle mass and strength in preclinical models.
How does ACE-031 differ from follistatin-344?
Both target the myostatin/activin axis but by different means. ACE-031 is an ActRIIB-Fc decoy receptor that traps ligands in circulation, whereas follistatin-344 is a natural glycoprotein that directly binds and neutralizes myostatin and activin with high affinity. They are frequently discussed together in muscle-growth research as two distinct mechanisms of myostatin inhibition.
How does follistatin-344 differ from ACE-031?
Follistatin-344 is a natural glycoprotein that directly binds and neutralizes myostatin and activin with picomolar affinity, whereas ACE-031 is an engineered ActRIIB-Fc decoy receptor that traps the same ligands in circulation. Both are common reference points in myostatin-inhibition research but represent different molecular strategies.
What is follistatin-344 (FST-344)?
Follistatin-344 is the 344-amino-acid isoform of follistatin, a naturally occurring secreted glycoprotein. It carries a heparin-binding N-terminal domain followed by three cysteine-rich follistatin domains that form its ligand-binding surface. It is studied as a high-affinity inhibitor of myostatin and activin A.
What is follistatin-344 studied for?
In research it is examined for its ability to bind and neutralize myostatin and activin A - TGF-beta superfamily members that restrain muscle growth - and thereby its effects on lean muscle mass in preclinical models. Human data are very limited and no injectable follistatin protocol has been validated in controlled clinical trials. It is a research-only compound.
Answers are the ones published on each compound's own PeptiDex entry. They are educational summaries of research-literature context and are not medical advice.