What is Follistatin-344? Activin-binding note

Research-use notice: This article is laboratory and educational information only. It is not medical or legal advice, and it does not include how-to-use instructions. BlueNex Labs materials are research use only and are not intended for human or veterinary use. Research-use-only labelling is not a Health Canada authorization.

Publication status: Prepared for the BlueNex Labs Research Knowledge Centre. Literature and library notes checked September 25, 2026. Primary papers and the public COA library can change; verify the lot report in hand before an assay.

Follistatin-344 is a precursor length, not a short synthetic peptide and not a catalogue SKU. The human FST gene produces more than one transcript. Alternative splicing yields a precursor of 344 amino acids and a shorter precursor of 317 amino acids. After the signal peptide is removed, the literature's mature isoforms are commonly follistatin-315, from the 344 precursor, and follistatin-288, from the 317 precursor. A further trimmed form, follistatin-303, has been described as a proteolytic piece of the longer mature chain. There is no follistatin shop SKU on this site.

What the isoforms are for in the papers

Follistatin was identified as a protein that binds activin and, in pituitary culture, can block activin-stimulated follicle-stimulating hormone release. Nakamura, Ueno, Shimasaki, and later structural groups mapped that binding. Harrington and colleagues solved a crystal structure of an activin dimer wrapped by follistatin domains, showing how the first two follistatin domains occlude a receptor site (EMBO Journal, 2006, DOI 10.1038/sj.emboj.7601000). That structure is a binding mechanism. It is not a use instruction.

Sidis and colleagues compared isoforms and follistatin-like-3 on activin, myostatin, and selected bone-morphogenetic proteins (PMID 16627583). Activin-binding affinities were similar across isoforms in that paper, while cell-surface binding was not: the shorter mature form bound cell-surface proteoglycans more tightly than follistatin-315, whose acidic C-terminal tail limits heparin binding. Myostatin competed for binding more strongly than some BMPs in their panel. Those differences are why an isoform name belongs on the tube. "Follistatin" alone does not say whether the chain includes the acidic tail.

Myostatin papers are not a catalogue claim

Myostatin, also called growth-differentiation factor 8, is a TGF-beta family ligand studied in skeletal-muscle cell systems because it restrains myogenic differentiation in those models. Follistatin can bind it. A binding result in a defined assay is not a statement about a person, and it is not a reason to sell a glycoprotein this shop does not list. For the muscle-biology reading list, which stays inside laboratory categories, see peptides in muscle-biology laboratory models. Secretagogue vials that are actually stocked are a different receptor class. See the secretagogue hub and the notes for AOD-9604 and IGF-1 LR3, which are also research-only.

Analytical expectations, without a hosted PDF

A follistatin lot file, if a laboratory obtains one elsewhere, should name the isoform (288, 303, or 315, or the 344 precursor if that is truly what was expressed), the expression system, glycosylation if it was characterized, and the mass or the electrophoretic result the laboratory trusts. Glycoproteins do not behave like a heptapeptide on a simple mass check. A single average mass without a glycan note can be ambiguous. This catalogue's COA library does not contain a follistatin row. A tesamorelin or ipamorelin PDF does not fill that gap.

The primer What is a peptide COA in Canada? still applies to the documents you do have for listed SKUs. It also explains why a missing row stays missing.

Legal and purchasing language

Advertising a follistatin preparation for human administration is a drug claim under the frame in Are research peptides legal in Canada?. Research-use-only wording on a third-party label does not create a DIN. BlueNex Labs does not provide administration guidance and does not provide this protein.

A purchase order that asks for "follistatin-344, Canada" should be answered with this URL and with a statement that the SKU is not sold. Redirecting that request to a secretagogue vial without saying the sequences differ would mis-file the order. The catalogue is available for materials that are listed under their own names.

What "344" should mean in a notebook

If a reference says follistatin-344, check whether the author means the precursor, the mature 315-residue isoform, or a supplier nickname that was never sequenced. Shimasaki's splicing description is the map: 344 and 317 are precursor counts; 315 and 288 are the mature counts after the signal peptide. Write the number you verified. Heparin-binding behaviour is a property of the shorter mature form in the papers above, not a slogan. Cell-surface binding assays and solution-binding assays answer different questions, which is the point of the Sidis comparison.

Storage language for lyophilized research solids this company does ship is in the Canadian storage note. It does not create a follistatin inventory.

Heparin binding is an isoform property

The shorter mature form's basic patch is why papers describe cell-surface retention. The longer mature form's acidic tail is why the same papers describe weaker heparin binding and a more circulating distribution in the models they used. If a methods section says only "follistatin was added," the reader cannot tell which distribution the author meant. Ask for the residue count. A 344-residue plasmid and a 315-residue purified protein can both be "correct" and still be different bottles.

Glycosylation adds another split. Ovarian isolations historically showed several masses from one gene because of sugars and because of the proteolytic trim to 303. A single SDS-PAGE band without a glycan note is a clue, not a full identity. None of that analytical work is hosted here. The point of stating it is to stop a short-peptide COA habit, the habit of trusting one mass peak, from being applied uncritically to a glycoprotein this shop does not sell.

Activin A, activin B, and myostatin are separate ligands. A file that shows neutralization of one does not document the others. Sidis and colleagues made that ligand panel the experiment. Cite the ligand you mean. Then state again, in the purchasing line, that BlueNex Labs has no follistatin SKU to attach the citation to.

Frequently asked questions

Does BlueNex Labs sell follistatin-344?

No. There is no follistatin shop SKU and no Product Offer. The page explains the isoform and the activin-binding literature.

Is follistatin-344 a short synthetic peptide?

No. The 344-residue figure is a precursor length from alternative splicing. Mature isoforms discussed in the papers are shorter chains, including follistatin-315 and follistatin-288, after signal-peptide cleavage. It is a glycoprotein, not a heptapeptide.

Does the GHS category include a follistatin vial?

No. The secretagogue shelf lists CJC-1295 without DAC paired with ipamorelin, ipamorelin, sermorelin, and tesamorelin. Those ligands are not follistatin.

What analytical point matters before any external lot is filed?

Record the isoform the report actually names, the observed mass, and whether a heparin-binding or cell-surface assay was run. A nickname on a label is not that record. This site does not host a follistatin PDF.

Catalogue cross-reference

Isoform questions stay on this page. Stocked secretagogue SKUs, which are not follistatin, are indexed on the secretagogue hub.

This page does not offer a vial, a price, or a Product Offer. Neighbouring materials that do have catalogue SKUs are listed on the research catalogue under their own names. A shared freezer box is not a shared certificate. Research use only. Not for human or veterinary use.