Function
While MGF is upregulated in muscle after mechanical overload, where it supports tissue repair and growth; recombinant forms are studied for regenerative and performance-enhancement effects22138, SS-31 improves mitochondrial bioenergetics, reduces oxidative stress, and shows protective effects in models of ischemia-reperfusion, neurodegeneration, and other mitochondrial disorders4637137.
Mechanism
While MGF works as a 24-amino-acid E-peptide splice variant of IGF-1 (IGF-1Ec) produced in mechanically stressed or damaged muscle that activates IGF1R and local anabolic pathways involved in muscle repair and hypertrophy22138144, SS-31 is a mitochondria-targeted tetrapeptide, d-Arg-dimethylTyr-Lys-Phe-NH2, that selectively binds cardiolipin in the inner mitochondrial membrane, stabilizing cristae structure, improving electron transport, and reducing ROS production4637137143.
Length and Sequence
MGF is 24 amino acids long, whereas SS-31 is shorter as it has a length of 4 amino acids. MGF is made up of a sequence of Tyrosine, Glutamine, Proline, Proline, Serine, Threonine, Asparagine, Lysine, Asparagine, Threonine, Lysine, Serine, Glutamine, Arginine, Arginine, Lysine, Glycine, Serine, Threonine, Phenylalanine, Glutamic acid, Glutamic acid, Arginine, Lysine. SS-31 is made up of a sequence of Arginine, dimethylTyr, Lysine, Phenylalanine.