Comparison
IGF-1 LR3 vs. MGF (Mechano Growth Factor)
Two peptides side-by-side — identity, evidence base, legal status and known adverse events.
Identity
Category
Growth
Growth
CAS no.
143045-27-6
12-Aminosäuren-C-terminales E-Domänen-Peptid (Sequenz nicht standardisiert)
Molecular weight
9117.6 g/mol
2867.2 g/mol
Half-life
21 h
0.1 h
Sequence
MFPAMPLSSLFVNGPRTLCGAELVDALQFVCGDRGFYFNKPTGYGSSSRRAPQTGIVDECCFRSCDLRRLEMYCAPLKPAKSAYQPPSTNKNTKSQRRKGSTFEERKMechanism of action
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.
MGF (Mechano Growth Factor)
The IGF-1 gene produces multiple isoforms by alternative splicing. IGF-1Ec is upregulated after mechanical muscle loading; the C-terminal E-domain is cleaved from the mature IGF-1 protein and appears to have independent effects on satellite cells. The exact receptor binding of the E-domain is not established; a classical IGF-1R effect is unlikely since mature IGF-1 is responsible. In cell-culture studies, stimulation of myoblast proliferation and differentiation has been observed.
Evidence base
Highest evidence
Animal model
Animal model
Studies
4
4
of which in humans
0
0
Effects recorded
4
3
Open conflicts
1
1
Documented adverse events
1
1
Legal status
Full entries
Frequently asked questions
- What is the difference between IGF-1 LR3 and MGF (Mechano Growth Factor)?
- IGF-1 LR3 is classified as "Growth", while MGF (Mechano Growth Factor) is classified as "Growth". 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. MGF (Mechano Growth Factor): Synthetic peptide corresponding to the C-terminal E-domain of the IGF-1 splice variant IGF-1Ec. Described in preclinical studies as a 'mechano-induced' skeletal muscle repair factor. No marketing approval; clinical use largely confined to the black market. This page contrasts both neutrally and source-based — with no usage or dosing recommendation.
- Which peptide is better supported by science, IGF-1 LR3 or MGF (Mechano Growth Factor)?
- The highest available evidence level is "Animal model" for IGF-1 LR3 and "Animal model" for MGF (Mechano Growth Factor). 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 IGF-1 LR3 and MGF (Mechano Growth Factor) in Germany and the United States?
- Germany: IGF-1 LR3 — Unapproved, MGF (Mechano Growth Factor) — Unapproved. United States: IGF-1 LR3 — Unapproved, MGF (Mechano Growth Factor) — Unapproved. These are factual summaries with source and review date on the individual pages.