What is follistatin 344?
A glycoprotein rather than a short peptide, and one that works by binding something else rather than by signalling on its own. That inverted mechanism is what makes it interesting and also what makes the claims around it hard to check.
A brake on the brake
Myostatin limits muscle growth. That is its physiological job: a negative regulator that keeps tissue from expanding without constraint. Follistatin binds myostatin and related proteins, which means it acts on the limiter rather than on growth itself.
The number in the name refers to an isoform. Follistatin exists in several lengths produced by different processing of the same gene, and 344 is one of them. Studies using different isoforms are not straightforwardly comparable.
Why the animal work travels badly
The striking results in this area come from genetic models: animals engineered to overexpress follistatin, or lacking functional myostatin. Those are powerful demonstrations that the pathway matters, and they say very little about what administering a protein would do.
A genetic model changes a system from conception. Introducing a protein into an adult organism is a different experiment with different constraints, and conflating the two is the single most common error in how this compound is discussed.
| Type | Glycoprotein |
| Length | 344 residues, one isoform of several |
| Mechanism | Binds myostatin and related proteins |
| Research models | Largely genetic overexpression models |
| Format | Pre-filled peptide pen |
| Purity | ≥ 99% (HPLC) |
| Evidence base | Animal work, mostly genetic rather than administered |
| Category | Research use only |
A description of the product, not a summary of findings.
A protein, with what that implies
At 344 residues this is a protein rather than a peptide, and considerably larger than anything else in the catalogue. Size drives stability, handling and how a molecule behaves in solution.
It also makes analysis harder. Confirming the identity and integrity of a glycoprotein is a more involved question than confirming a short sequence, which is worth knowing when you read any certificate for this material.
Follistatin 344 in the catalogue
We hold every lot to 99% by HPLC and keep the matching paperwork on file.
Where this fits in
Background reading, if the ground here felt unfamiliar.
About Follistatin 344
The questions that reach our support desk.
Do the animal results transfer?
What does the 344 mean?
Is it a peptide?
Why is the pen a smaller quantity than others?
Ask for the batch number
A protein that acts on a limiter rather than a signal. The genetic literature is striking and it is not the same experiment as administering the material.
For laboratory and research use only. Not for human or animal consumption. Not a medicine and not a food supplement. Sold to persons aged 18 and over.


