Follistatin-344
Also known as FS-344, follistatin isoform 344, FST-344
Follistatin-344 is a recombinant isoform of the activin-binding glycoprotein follistatin, studied in the context of the myostatin/activin (TGF-β) signaling system. A research-use profile.
Follistatin-344 is a protein, not a peptide in the small-molecule sense, and that distinction shapes everything about it. Where most catalog compounds are short synthetic chains, follistatin is a folded, multi-domain secreted glycoprotein, and the '344' names a specific naturally occurring isoform of it. Its research relevance is defined by what it binds.
This page describes that binding role within the activin/myostatin signaling system. It does not describe outcomes — follistatin biology is an active experimental field, and the meaningful, verifiable content here is the protein's identity and the pathway it participates in.
One of the naturally occurring isoforms of follistatin, a secreted activin-binding glycoprotein. The 344-residue form (before signal-peptide processing) represents the longer, less membrane-associated variant of the protein; it is a folded, multi-domain protein rather than a short synthetic peptide.
An activin- and myostatin-binding protein
Follistatin's defining biochemical property is that it binds members of the TGF-β superfamily — most notably activin, and also myostatin (GDF-8). By binding these ligands, follistatin is studied as a natural antagonist within that signaling network: it is one of the endogenous molecules that modulates how much of these signals reach their receptors. This binding role is the reason follistatin appears in myostatin- and activin-focused research at all.
The myostatin connection is why follistatin is grouped with performance and muscle-biology research contexts. Myostatin is a well-studied regulator in that field, and follistatin is one of its recognized binding partners — a relationship of molecular interaction, described here without any claim about downstream results.
Why the '344' isoform matters
Follistatin exists as more than one isoform, generated from the same gene. The 344 designation refers to the longer form of the mature protein sequence. Isoforms of follistatin differ in properties such as how strongly they associate with cell surfaces, which is why researchers specify the isoform rather than referring to 'follistatin' generically — FS-344 and the shorter FS-315 form are studied as distinct entities.
Because it is a full protein with multiple structured domains, follistatin-344 is not represented by a short one-letter sequence the way a small peptide would be; it is identified by its isoform designation and its recombinant origin.
These are research areas the compound is associated with in the literature — not medical claims or intended uses.
Handling & storage
As a recombinant protein it is supplied lyophilized and is handled with extra care for a folded, multi-domain structure: kept sealed, cold, and dry, reconstituted only when a protocol requires it, and not subjected to repeated freeze–thaw. Handle per accepted laboratory practice.
Verify a certificate by lot →Common questions
It is a protein — a folded, multi-domain secreted glycoprotein — rather than a short synthetic peptide, which is why it is described by isoform rather than a one-letter sequence.
It binds members of the TGF-β superfamily, including activin and myostatin (GDF-8), acting as a natural binding partner within that signaling network.
It is a specific naturally occurring isoform of follistatin — the longer mature form — distinguished from the shorter FS-315 isoform in the research literature.
This monograph is a research-use reference. It describes composition and the contexts in which the compound has been studied — it is not medical advice, a description of effects, or a recommendation for use. Sold strictly for laboratory and research use; not for human or animal consumption.