MGF (Mechano Growth Factor) Research Guide: The IGF-1Ec E-Domain Peptide
By UK Peptide Lab Research Team•19 September 2026•8 min read
Key Takeaways
- MGF is the 24-residue C-terminal E-domain peptide of the IGF-1Ec splice variant, sequence YQPPSTNKNTKSQRRKGSTFEEHK, MW 2866.4 g/mol, cloned and named by the Goldspink group (Yang et al., J Muscle Res Cell Motil, 1996).
- The founding functional study reported that the synthetic E-peptide increased myoblast proliferation while mature IGF-1 promoted differentiation (Yang and Goldspink, FEBS Lett, 2002), and MGF expression coincides with satellite cell activation after muscle damage (Hill and Goldspink, J Physiol, 2003).
- The evidence base is thin and contested: a careful replication found no effect on myoblasts or primary muscle stem cells (Fornaro et al., Am J Physiol Endocrinol Metab, 2014), and the balanced review by Matheny, Nindl and Adamo (Endocrinology, 2010) judges the in-vivo evidence inadequate.
- Supplied for in-vitro laboratory research only; no dosing information, no human-use claims, no therapeutic promises.
What is MGF?
MGF, short for mechano growth factor, is the 24-residue C-terminal peptide of the human IGF-1Ec splice variant, sequence Tyr-Gln-Pro-Pro-Ser-Thr-Asn-Lys-Asn-Thr-Lys-Ser-Gln-Arg-Arg-Lys-Gly-Ser-Thr-Phe-Glu-Glu-His-Lys, written YQPPSTNKNTKSQRRKGSTFEEHK, molecular weight 2866.4 g/mol. Structurally it is part of the E-domain of the IGF-1 precursor, the region cleaved away when the mature 70-residue IGF-1 hormone is processed, and no CAS registry number is published for the peptide. The sequence is strongly basic, with four lysine and two arginine residues, and carries no methionine, cysteine or tryptophan. UK Peptide Lab supplies MGF 2mg as lyophilised powder for in-vitro laboratory research only.
Origin: Alternative Splicing of the IGF-1 Gene
The IGF-1 gene is transcribed as a precursor that is spliced into several isoforms, and the exercise-sensitive splice form is the starting point of the MGF story. Yang and colleagues (J Muscle Res Cell Motil, 1996) cloned and characterised an IGF-1 isoform expressed in skeletal muscle subjected to stretch, and the group named the splice variant mechano growth factor for its induction by mechanical load. Goldspink's review (Physiology, 2005) sets out the model that has guided the field since: mechanical signals shift IGF-1 splicing towards the Ec form, the E-domain peptide acts locally in the loaded muscle, while the mature hormone acts systemically through the circulation.
The splicing hypothesis itself is well supported; the extent to which the free E-peptide exists and acts in vivo is the contested part, as covered below.
Satellite Cell Activation and Proliferation
The main experimental claims concern muscle repair. Yang and Goldspink (FEBS Lett, 2002) treated myoblast cultures with the synthetic E-peptide and reported increased cell proliferation, while mature IGF-1 promoted differentiation, leading them to propose that the two products of the IGF-1 gene play complementary roles: the E-peptide first expanding the pool of muscle precursor cells, the mature hormone then driving their fusion into myotubes. Hill and Goldspink (J Physiol, 2003) extended the story in vivo, measuring IGF-1 splice-variant expression in rodent muscle after local tissue damage and reporting that the MGF transcript appeared alongside markers of muscle satellite (stem) cell activation. Owino, Yang and Goldspink (FEBS Lett, 2001) added the ageing angle: muscles of old rats expressed markedly less MGF in response to mechanical overload than young muscle, which the authors linked to the attenuated repair of aged muscle.
MGF vs Mature IGF-1
Chemically these are different molecules from the same gene. Mature IGF-1 is the 70-residue hormone that signals through the IGF-1 receptor; MGF is the 24-residue E-domain peptide, and the literature reports that its proliferation effects are not mediated through the IGF-1 receptor in the manner of the mature hormone, with no dedicated MGF receptor identified to date. The cleanest demonstration is the founding study itself: identical myoblast cultures responded to the two molecules with different outputs (Yang and Goldspink, FEBS Lett, 2002). For study design the practical point is that IGF-1 LR3 is a modified form of the mature hormone, not an MGF analogue, and the two are not interchangeable tools.
Reading the Evidence Honestly
The honest summary of this literature is that it is thin and contested, and it should be read as such. The primary positive data originate mostly from one research group, in rodent models and cell culture, and no human data of any kind exist for the peptide. A careful negative study by Fornaro and colleagues (Am J Physiol Endocrinol Metab, 2014) tested both native and stabilised MGF peptides on myoblasts and primary muscle stem cells and reported no effect on proliferation or activation, in systems where mature IGF-1 produced a robust response. The most balanced review of the field, by Matheny, Nindl and Adamo (Endocrinology, 2010), concluded that there is inadequate evidence to establish that MGF is produced from the IGF-1 gene in vivo or that it plays a role in tissue repair.
That is not a dismissal of the compound; it is a description of where the evidence stands, and it is why this guide carries no dosing information, no human-use claims and no outcome promises. MGF holds no marketing authorisation anywhere, and the material is supplied for in-vitro laboratory research only.
MGF vs PEG-MGF
PEG-MGF is the same 24-residue sequence with a polyethylene glycol moiety conjugated to it. PEGylation slows enzymatic degradation and extends the peptide's lifetime in solution and circulation, at the cost of departing from the exact molecule used in the primary literature. The unmodified MGF peptide is the reference molecule: it is the form used in the proliferation and satellite-cell studies above, and it is the correct choice for laboratories replicating published work. PEG-MGF suits designs where solution stability or extended exposure is the priority, with the added pharmacokinetic variable that entails.
Laboratory Handling, Reconstitution and Storage
Store the lyophilised vial at -20°C, protected from light and moisture. Reconstitute by slowly injecting bacteriostatic water down the inner glass wall and swirling gently until dissolved; never shake or vortex. The sequence has no methionine, cysteine or tryptophan, so it lacks strongly oxidation-prone residues, and sterility is the practical constraint on solution life. Store the reconstituted solution at 2-8°C and use within 4 weeks, preparing single-use aliquots for longer storage. See the peptide reconstitution guide and the peptide storage guide for full methodology.
Sourcing Research-Grade MGF in the UK
UK Peptide Lab supplies MGF 2mg at £24.99 as lyophilised powder, supplier-tested, batch UKPL-9507 at 99.36% purity by HPLC, with the supplier certificate of analysis published on the product page and independent third-party verification pending. Orders placed before 2pm GMT dispatch the same day, with free Royal Mail Tracked shipping on UK orders over £45. MGF is supplied strictly for in-vitro laboratory research use, is not a licensed medicine anywhere, and purchasers must be 18 or over.
Related Products
Disclaimer: This article is for research and educational purposes only. All information provided is not intended as medical advice. UK Peptide Lab products are not for human consumption and are sold strictly for laboratory research use only.
Frequently Asked Questions
What is MGF?
MGF, mechano growth factor, is the 24-residue C-terminal E-domain peptide of the IGF-1Ec splice variant of insulin-like growth factor 1, sequence YQPPSTNKNTKSQRRKGSTFEEHK, molecular weight 2866.4 g/mol. It is the peptide cleaved from the IGF-1 precursor during processing of the mature 70-residue hormone, and it was cloned from stretched skeletal muscle and named by the Goldspink group (Yang et al., J Muscle Res Cell Motil, 1996). Supplied as lyophilised powder for in-vitro laboratory research only; it holds no marketing authorisation in any jurisdiction.
Does MGF activate satellite cells in muscle research?
The founding studies report that it does in their systems: the synthetic E-peptide increased myoblast proliferation while mature IGF-1 promoted differentiation (Yang and Goldspink, FEBS Lett, 2002), and MGF expression coincided with satellite (stem) cell activation markers after local muscle damage (Hill and Goldspink, J Physiol, 2003). The caveat is replication: Fornaro and colleagues (Am J Physiol Endocrinol Metab, 2014) found no effect of native or stabilised MGF peptides on myoblasts or primary muscle stem cells, so the finding is contested rather than established.
Is MGF legal to buy in the UK?
MGF is not a Controlled Drug, and it may lawfully be bought and held in the UK as a research chemical for in-vitro laboratory use. It is not a licensed medicine anywhere, and under the Human Medicines Regulations 2012 it cannot lawfully be sold or supplied for human consumption. Purchasers must be 18 or over and confirm research-only use at checkout.
References
- [1] Cloning and characterization of an IGF-1 isoform expressed in skeletal muscle subjected to stretch. J Muscle Res Cell Motil (1996). View →
- [2] Different roles of the IGF-I Ec peptide (MGF) and mature IGF-I in myoblast proliferation and differentiation. FEBS Lett (2002). View →
- [3] Expression and splicing of the insulin-like growth factor gene in rodent muscle is associated with muscle satellite (stem) cell activation following local tissue damage. J Physiol (2003). View →
- [4] Mechano-growth factor peptide, the COOH terminus of unprocessed insulin-like growth factor 1, has no apparent effect on myoblasts or primary muscle stem cells. Am J Physiol Endocrinol Metab (2014). View →
- [5] Minireview: Mechano-Growth Factor: A Putative Product of IGF-I Gene Expression Involved in Tissue Repair and Regeneration. Endocrinology (2010). View →