Myostatin (GDF-8), a member of the TGF- beta superfamily, is a potent and specific negative regulator of skeletal muscle mass. The myostatin propeptide is known to bind and inhibit myostatin in vitro. This interaction is relevant in vivo, with a majority (>70%) of myostatin in serum bound to its propeptide acting as a negative regulator of myostatin. Recombinant Myostatin Propeptide is a non-glycosylated Protein, containing 244 amino acids, with a molecular weight of 27.8 kDa.