FOXO4

Myostatin is a kind of TGF-β family discovered as a factor involved in the modulation of the number of muscles. It inhibits the growth of skeletal muscles, and in knockout mice, an increase in skeletal muscles and a decrease in body fat mass have been reported. Myostatin activity is inhibited by follistatin, an activin-binding protein and myostatin propeptide. Growth Differentiation Factor 8 (GDF-8), also known as myostatin, is a member of the TGF-beta superfamily expressed specifically in developing and adult skeletal muscle. GDF-8 cDNA encodes a 376 amino acid (aa) prepropeptide with a 24 aa residue signal peptide, a 223 aa residue amino-terminal propeptide, and a 109 aa residue carboxy-terminal mature protein. Mature GDF-8 contains the canonical 7-cysteine motif common to other TGF-beta superfamily members.