Confronto
Follistatin (FST) vs. IGF-1 LR3
Due peptidi a confronto — identità, base di evidenze, stato legale ed eventi avversi noti.
Identità
Categoria
Crescita
Crescita
N. CAS
122956-17-2
143045-27-6
Peso molecolare
35000 g/mol
9117.6 g/mol
Emivita
nessun dato
21 h
Sequenza
Glykoprotein, ~315 Aminosäuren in der zirkulierenden Hauptform (Sequenz isoformabhängig, kein einheitliches kurzes Peptid)MFPAMPLSSLFVNGPRTLCGAELVDALQFVCGDRGFYFNKPTGYGSSSRRAPQTGIVDECCFRSCDLRRLEMYCAPLKPAKSAMeccanismo d'azione
Follistatin (FST)
Follistatin binds with high affinity to activin and to myostatin (GDF-8), as well as related TGF-β ligands such as GDF-11 and some BMPs, preventing their binding to the activin type-II receptors. Myostatin is a negative regulator of skeletal muscle mass; by sequestering myostatin, its growth-inhibiting signalling is removed (de-repression). Because follistatin additionally neutralises activin, it acts on several muscle-inhibiting pathways at once — in animal models this produced greater muscle gain than knocking out myostatin alone. Several isoforms exist (including FST-288 and FST-315) that differ in tissue binding via heparan sulfate. The FST344 variant used in gene therapy was chosen to reduce binding to off-target structures.
IGF-1 LR3
IGF-1 LR3 is a recombinantly produced variant of human IGF-1. Two changes define its properties: (1) at position 3, glutamic acid is replaced by arginine; (2) a 13-amino-acid sequence is added at the N-terminus ('Long'). Both modifications drastically reduce affinity for the six IGF-binding proteins (IGFBP-1 to -6) that normally bind native IGF-1 in the blood and regulate its availability at the receptor. As a result, a larger fraction of the molecule is freely available to bind the type-1 IGF receptor (IGF-1R) — the same receptor as native IGF-1. In preclinical models and cell culture, LR3 IGF-1 therefore acts as a more potent agonist than unmodified IGF-1. The downstream signalling pathway (PI3K/Akt and MAPK) is identical to that of IGF-1; the modification changes bioavailability, not the receptor target.
Base di evidenze
Evidenza più alta
Studio sull'uomo
Modello animale
Studi
4
4
di cui sull'uomo
1
0
Effetti registrati
4
4
Contraddizioni aperte
1
1
Eventi avversi documentati
1
1
Stato legale
Voci complete
Frequently asked questions
- What is the difference between Follistatin (FST) and IGF-1 LR3?
- Follistatin (FST) is classified as "Crescita", while IGF-1 LR3 is classified as "Crescita". Follistatin (FST): Follistatin is an endogenous glycosylated binding protein (~35 kDa, considerably larger than typical peptides) that binds and neutralises members of the TGF-β superfamily, including activin and myostatin (GDF-8). In animal models, raising follistatin de-represses muscle growth. Clinically it has been studied mainly via AAV gene therapy (FS344) in muscular dystrophies. Follistatin is not an approved drug; human efficacy and safety data are limited and stem mostly from early gene-therapy trials and preclinical research. A 'follistatin-344' product is sold on the grey market, the identity and purity of which cannot be verified without analytics. IGF-1 LR3: Synthetic analogue of insulin-like growth factor 1 (IGF-1) carrying an arginine substitution at position 3 and a 13-amino-acid N-terminal extension. These modifications lower binding to IGF-binding proteins and extend its duration of action relative to native IGF-1. LR3 IGF-1 is primarily an established cell-culture reagent (serum-free media, bioprocessing); it is NOT an approved human medicine. Use in the bodybuilding grey market is described; as an IGF-1 analogue, LR3 IGF-1 falls under the WADA anti-doping prohibition. This page contrasts both neutrally and source-based — with no usage or dosing recommendation.
- Which peptide is better supported by science, Follistatin (FST) or IGF-1 LR3?
- The highest available evidence level is "Studio sull'uomo" for Follistatin (FST) and "Modello animale" for IGF-1 LR3. A higher evidence level means more robust data, but says nothing about suitability for an individual. The full body of evidence is on each peptide's own page.
- What is the legal status of Follistatin (FST) and IGF-1 LR3 in Germany and the United States?
- Germania: Follistatin (FST) — Non approvato, IGF-1 LR3 — Non approvato. Stati Uniti: Follistatin (FST) — Non approvato, IGF-1 LR3 — Non approvato. These are factual summaries with source and review date on the individual pages.