Function
While GHRP-2 is used in research to induce robust GH pulses and study anabolic and metabolic effects; clinically developed as pralmorelin for GH deficiency diagnostics6272, PEG-MGF is used experimentally to enhance muscle repair and hypertrophy after mechanical overload or injury by stimulating satellite-cell activation and protein synthesis6373138.
Mechanism
While GHRP-2 works as a second-generation hexapeptide growth hormone–releasing peptide that mimics ghrelin by agonizing GHSR-1a, strongly stimulating pulsatile GH release and modestly raising prolactin, ACTH, and cortisol62723096, PEG-MGF is a poly(ethylene glycol)-conjugated form of Mechano Growth Factor (IGF-1Ec splice variant) comprising the 24-aa C-terminal E-peptide of IGF-1, designed to extend half-life while activating IGF-1 receptor–mediated anabolic signaling in muscle satellite cells637322138.
Length and Sequence
GHRP-2 is 6 amino acids long, whereas PEG-MGF is longer as it has a length of 24 amino acids. GHRP-2 is made up of a sequence of Alanine, D-2-Nal, Alanine, Tryptophan, Phenylalanine, Lysine. PEG-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.