Myostatin, also called growth differentiation factor 8 (GDF-8), is a secreted TGF-beta superfamily ligand produced mainly by skeletal muscle. It is synthesised as a precursor, cleaved by furin into a propeptide and a mature disulfide-linked dimer, and then circulates in a latent complex with its own propeptide until BMP-1/tolloid proteases release the active dimer.
Why myostatin matters
Active myostatin binds the activin type IIB receptor, recruits ALK4 or ALK5, and phosphorylates SMAD2/3, which represses muscle differentiation programmes and interacts with Akt/mTOR signalling. Its role as a negative regulator was established by loss-of-function phenotypes: the 1997 knockout mouse, double-muscled Belgian Blue and Piedmontese cattle, whippets carrying the mutation, and a single reported human case in 2004.
That biology made inhibition an obvious therapeutic hypothesis, and multiple antibody, receptor-decoy and follistatin-based programmes reached human trials. Results have been consistent in one direction: lean mass increases were reported, functional and strength endpoints largely did not follow, and several programmes were discontinued. Research-grade GDF-8 propeptide and related reagents are supplied for in vitro and preclinical work only.
Related terms and material
IGF-1 · recombinant · preclinical. Reference material: GDF-8 / myostatin propeptide, ACE-031, IGF & muscle peptides. Further reading: peptides for muscle growth research.