Research Guides

PEG-MGF Research Guide: The PEGylated IGF-1Ec E-Domain Peptide

By UK Peptide Lab Research Team•19 September 2026•8 min read
PEG-MGF Research Guide: The PEGylated IGF-1Ec E-Domain Peptide · research peptide

Key Takeaways

  • PEG-MGF is the 24-residue IGF-1Ec E-domain peptide (YQPPSTNKNTKSQRRKGSTFEEHK, ~2866 g/mol unmodified) conjugated to polyethylene glycol, raising the mass to roughly 9.8 kDa.
  • The splice variant was cloned from stretched muscle by Yang et al. (J Muscle Res Cell Motil, 1996); the E-domain peptide drives myoblast proliferation while blocking differentiation (Yang and Goldspink, FEBS Lett, 2002).
  • Satellite cell activation is the central claim (Hill and Goldspink, J Physiol, 2003; Kandalla et al., Mech Ageing Dev, 2011), but a pharmaceutical-company replication reported no effect on myoblasts or primary muscle stem cells (Fornaro et al., Am J Physiol Endocrinol Metab, 2014).
  • The PEGylated form has no dedicated peer-reviewed literature; supplied for in-vitro laboratory research only, with no dosing information, no human-use claims and no therapeutic promises.

What is PEG-MGF?

PEG-MGF is the PEGylated form of mechano growth factor (MGF), the 24-residue C-terminal E-domain peptide of the IGF-1Ec splice variant of insulin-like growth factor 1. The underlying peptide has the 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, with a molecular weight of approximately 2866 g/mol. Conjugation of polyethylene glycol raises the mass of the product to roughly 9.8 kDa, and as a conjugate it carries no CAS registry number on the listing. UK Peptide Lab supplies PEG-MGF 2mg as lyophilised powder for in-vitro laboratory research use only.

Splice Biology: Where MGF Comes From

Mechano growth factor exists because the IGF-1 gene is spliced differently in muscle under mechanical load. The IGF-1Ec transcript carries a 49-base insert in the human sequence, and because the insert length is not a multiple of three, the reading frame shifts and the C-terminal E domain is encoded in a different frame from the systemic IGF-1Ea isoform. The variant was first cloned from rabbit muscle subjected to stretch by Yang, Alnaqeeb, Simpson and Goldspink (J Muscle Res Cell Motil, 1996). Goldspink's later review (Physiology, 2005) summarises the expression programme: MGF mRNA appears as an early pulse after muscle damage, followed by a switch of splicing toward IGF-1Ea, and the two isoforms are proposed to do different jobs at different times in the repair response.

The E-Domain Peptide as a Proliferation Signal

The peptide literature focuses on the E-domain peptide itself, which was proposed to act independently of the mature IGF-1 protein and its receptor. Yang and Goldspink (FEBS Lett, 2002) reported that the IGF-I Ec peptide stimulated proliferation of C2C12 myoblasts while blocking their differentiation, the opposite balance to mature IGF-I, which drives both. Ates and colleagues (FEBS Lett, 2007) reported increased progenitor cell numbers in cultures derived from normal, dystrophic and ALS muscle, again with differentiation suppressed relative to IGF-I. The proposed receptor for the E peptide has never been conclusively identified, which is one reason the mechanism remains contested.

Satellite Cells and Muscle Repair

The satellite cell connection is the line of work most often cited. Hill and Goldspink (J Physiol, 2003) showed that the MGF splice variant is expressed as an early pulse following local muscle damage in rodents, in association with markers of satellite (stem) cell activation. In primary human muscle cell culture, Kandalla, Goldspink, Butler-Browne and Mouly (Mech Ageing Dev, 2011) reported that the E peptide increased the proliferative lifespan and delayed senescence of satellite cells from neonatal and young adult donors, while cells from old adult muscle did not respond, an age dependence that matters to anyone planning a sarcopenia-related design. Mills and colleagues (Am J Transplant, 2007) reported improved engraftment of transplanted myogenic precursor cells in mice treated with the E peptide.

Why PEGylate?

The PEGylation step addresses a pharmacokinetic problem, not a chemical one. The unmodified E peptide is cleared from circulation within minutes, which confines most published work to cell culture or local delivery. Conjugation of polyethylene glycol increases the hydrodynamic radius of the peptide, reduces renal filtration and slows proteolytic degradation, the standard rationale reviewed by Harris and Chess (Nat Rev Drug Discov, 2003). The resulting conjugate runs at roughly 9.8 kDa against approximately 2866 g/mol unmodified. The practical cost is assay behaviour: the conjugate migrates differently on gels, the polymer can interfere with antibody-based detection, and results obtained with the PEGylated form cannot be cited against the unmodified literature one to one.

Reading the Evidence Honestly

The honest position on this compound is that the evidence is thinner than vendor literature usually admits. A replication attempt conducted at two pharmaceutical companies tested the MGF C-terminal peptide up to 500 ng/ml in C2C12 cells, primary human myoblasts and primary mouse muscle stem cells and found no effect on proliferation or differentiation, while mature IGF-1 responded normally in every system (Fornaro et al., Am J Physiol Endocrinol Metab, 2014). The authors concluded that the physiological role of MGF itself should be questioned. There are no clinical trials of MGF or PEG-MGF, and the field's own review literature describes MGF as a putative repair factor (Matheny, Nindl and Adamo, Endocrinology, 2010). PEG-MGF specifically has no dedicated peer-reviewed publications at all; its behaviour in any assay is an extrapolation from the unmodified peptide and from general PEGylation pharmacology. Accordingly this guide carries no dosing information, no human-use claims and no therapeutic promises.

Laboratory Handling

Store lyophilised vials at -20°C, protected from light and moisture, for up to 24 months. Reconstitute with Bacteriostatic Water injected slowly down the inner wall of the vial, then swirl gently until the solution is clear and colourless; never shake or vortex, and avoid vigorous agitation of reconstituted PEG conjugates. The 24-residue sequence contains no methionine, cysteine or tryptophan, so there are no oxidation-prone residues or disulfides to manage; the handling considerations are the PEG moiety and sterility. Hold the reconstituted solution at 2-8°C and use within 4 weeks, preparing single-use aliquots for longer work. See the peptide storage guide for general principles.

Sourcing in the UK

UK Peptide Lab supplies research-grade PEG-MGF 2mg as lyophilised powder, supplier-tested, batch UKPL-9506 at 99.77% purity by HPLC, with the certificate of analysis published on the product page and independent third-party verification pending. Same-day UK dispatch on orders placed before 2pm GMT, free Royal Mail Tracked shipping over £45. For in-vitro laboratory research use only, not for human consumption.

Related Products

PEG-MGF MGF IGF-1 LR3 Bacteriostatic Water

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 PEG-MGF?

PEG-MGF is the PEGylated form of mechano growth factor (MGF), the 24-residue C-terminal E-domain peptide of the IGF-1Ec splice variant of insulin-like growth factor 1. The underlying sequence is YQPPSTNKNTKSQRRKGSTFEEHK, approximately 2866 g/mol unmodified and roughly 9.8 kDa in the PEGylated form supplied here. The splice variant was first cloned from stretched rabbit muscle by Yang, Alnaqeeb, Simpson and Goldspink (J Muscle Res Cell Motil, 1996). It is supplied as lyophilised powder for in-vitro laboratory research only, and carries no CAS registry number on the listing.

What does the PEGylation do?

PEGylation is a pharmacokinetic modification. The unmodified E-domain peptide is cleared within minutes, and conjugation of polyethylene glycol raises the hydrodynamic radius, reduces renal filtration and slows proteolytic degradation, the general strategy reviewed by Harris and Chess (Nat Rev Drug Discov, 2003). The peptide sequence is unchanged, but the PEGylated form does not appear in the primary MGF literature, so its behaviour in any assay is an extrapolation rather than an established finding.

Is the evidence for MGF solid?

It is mixed, and the honest reading matters for experimental design. The founding in-vitro claims, myoblast proliferation and satellite cell activation, come from Yang and Goldspink (FEBS Lett, 2002), Hill and Goldspink (J Physiol, 2003) and Kandalla et al. (Mech Ageing Dev, 2011). Against them stands a study from two pharmaceutical companies that found no effect of the MGF C-terminal peptide on C2C12 cells, primary human myoblasts or primary mouse muscle stem cells, and concluded the physiological role of MGF itself should be questioned (Fornaro et al., Am J Physiol Endocrinol Metab, 2014). There are no clinical trials of MGF or PEG-MGF.

How should PEG-MGF be reconstituted and stored?

Store lyophilised vials at -20°C, protected from light and moisture, for up to 24 months. Reconstitute with bacteriostatic water injected slowly down the inner glass wall, then swirl gently until clear and colourless; never shake or vortex, and avoid vigorous agitation of PEG conjugates. Hold the reconstituted solution at 2-8°C and use within 4 weeks, preparing single-use aliquots for longer work. Supplied for in-vitro laboratory research use only.

References

  1. [1] Cloning and characterization of an IGF-1 isoform expressed in skeletal muscle subjected to stretch. J Muscle Res Cell Motil (1996). View →
  2. [2] Different roles of the IGF-I Ec peptide (MGF) and mature IGF-I in myoblast proliferation and differentiation. FEBS Lett (2002). View →
  3. [3] Effect of pegylation on pharmaceuticals. Nat Rev Drug Discov (2003). View →
  4. [4] 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 →
  5. [5] Minireview: Mechano-Growth Factor: A Putative Product of IGF-I Gene Expression Involved in Tissue Repair and Regeneration. Endocrinology (2010). View →
  6. [6] Mechano Growth Factor E peptide (MGF-E), derived from an isoform of IGF-1, activates human muscle progenitor cells and induces an increase in their fusion potential at different ages. Mech Ageing Dev (2011). View →
  7. [7] 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 →

More Research Articles

Laboratory Guides

Peptide Storage Guide: How to Store Research Peptides Correctly

8 min read

Laboratory Guides

Are Peptides Legal in the UK? The Actual Legal Position

9 min read