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PeptideHormone

Mechano growth factorMGF

IGF-1's local, load-triggered splice variant — a repair pulse, not a systemic signal.

Research peptidePreclinicalBased on Insulin-like growth factor 1Compare lineage

The same growth message the muscle already knows, re-spliced on the spot when the fibre is worked — a local dialect the tissue writes for itself, and one the field is still learning to read.

Identity

Class
IGF-1 splice variant (IGF-1Ec); the research peptide is its C-terminal E-domain (~24 aa)
Source
Made locally in muscle after mechanical overload or damage
Receptor
The IGF-1 core acts at IGF-1R; the distinct E-domain peptide's receptor is unidentified

Key properties

Evidence floorClinicalCLIN1
Half-life (native)
Minutes (E-domain peptide); longer as PEG-MGF
CLIN

Approximate values for the native hormone; engineered analogs are often deliberately larger and far longer-acting. Each figure carries its own provenance tier, and the floor is the weakest of them - the Standard.

Mechanism

Mechanical loading of muscle switches the IGF-1 gene's splicing toward the Ec exon, producing MGF — the same IGF-1 core carried on a different C-terminal E-domain. The mature E-domain peptide appears to act on its own, activating and proliferating satellite cells to seed repair, and it does so even in cells lacking the IGF-1 receptor — so it is not simply local IGF-1. The synthetic 'MGF' sold for research is that E-domain peptide.

Reference notes

  • MGF is not a separate gene but an alternatively spliced product of IGF-1, distinguished entirely by its E-domain — the pulse a fibre makes when it is worked or injured.
  • The E-domain peptide's satellite-cell and neuroprotective effects appear in cells without IGF-1R, implying a receptor of its own that has never been pinned down — genuinely open biology.
  • The synthetic peptide is short-lived (minutes), which is why a pegylated form ('PEG-MGF') exists; human efficacy for either is unproven, and the 'distinct hormone' framing is still debated.

Common questions

What is Mechano growth factor (MGF)?
IGF-1's local, load-triggered splice variant — a repair pulse, not a systemic signal. Structurally it is IGF-1 splice variant (IGF-1Ec); the research peptide is its C-terminal E-domain (~24 aa).
How does MGF work?
Mechanical loading of muscle switches the IGF-1 gene's splicing toward the Ec exon, producing MGF — the same IGF-1 core carried on a different C-terminal E-domain. The mature E-domain peptide appears to act on its own, activating and proliferating satellite cells to seed repair, and it does so even in cells lacking the IGF-1 receptor — so it is not simply local IGF-1. The synthetic 'MGF' sold for research is that E-domain peptide.
How strong is the evidence for MGF?
PeptideHormone grades MGF at the "Preclinical" evidence tier — the evidence is largely animal or in-vitro, with human data thin or absent. It is catalogued as a community research peptide outside the approved-drug system, and the tier is an editorial judgment about the public literature that can change as the science does.
What is the half-life of MGF?
The reported circulating half-life of MGF is Minutes (E-domain peptide); longer as PEG-MGF.

Selected literature

Curated peer-reviewed reviews, sourced from PubMed. Selected for relevance, not exhaustive — open any entry on PubMed for the full record and its primary citations.

  1. 1.Minireview: Mechano-growth factor: a putative product of IGF-I gene expression involved in tissue repair and regeneration · Endocrinology, 2010 · PMID 20130113
  2. 2.Expression of insulin growth factor-1 splice variants and structural genes in rabbit skeletal muscle induced by stretch and stimulation · The Journal of physiology, 1999 · PMID 10087355
  3. 3.Mechano-growth factor, an IGF-I splice variant, rescues motoneurons and improves muscle function in SOD1(G93A) mice · Experimental neurology, 2009 · PMID 19038252