IGF & Myostatin Pathway Kit

IGF-1 LR3 is a synthetic 83-amino acid analog of IGF-1 (which has 70 amino acids) with an arginine at position 3 and a 13-amino acid extension at the N-terminus. These modifications reduce binding to IGF binding proteins (IGFBPs) by over 100-fold, resulting in dramatically higher bioavailability and potency compared to native IGF-1. It activates the IGF-1 receptor to stimulate the PI3K/Akt and MAPK/ERK pathways, promoting cell proliferation, differentiation, survival, and protein synthesis in muscle and other tissues.

MGF is a splice variant of IGF-1 produced in mechanically stressed muscle tissue. Its unique E-domain (C-terminal peptide) activates satellite cells (muscle stem cells) and drives their proliferation while preventing premature differentiation. This is distinct from IGF-1Ea, which primarily drives differentiation. MGF also has neuroprotective properties and can protect cortical and hippocampal neurons. It acts through receptor-mediated signaling that is partially independent of the classical IGF-1 receptor.

PEG-MGF shares the same mechanism as MGF (satellite cell activation, muscle repair, neuroprotection) but has been modified through PEGylation, which involves covalent attachment of polyethylene glycol chains. This modification shields the peptide from enzymatic degradation, reduces renal clearance, and dramatically extends its half-life from minutes to hours. The sustained exposure allows for systemic distribution and more prolonged satellite cell activation.

ACE-031 is a soluble decoy receptor consisting of the extracellular domain of activin receptor type IIB (ActRIIB) fused to a human IgG1 Fc domain. It functions as a ligand trap, binding and neutralizing myostatin (GDF-8), activin A, GDF-11, and other TGF-beta superfamily ligands that negatively regulate muscle-signaling. By sequestering these ligands in the circulation, ACE-031 removes the natural brake on muscle-signaling, resulting in significant increases in muscle mass and strength. The Fc domain provides extended half-life through FcRn recycling.