Follistatin is a single-chain gonadal protein that specifically inhibits follicle-stimulating hormone release.
The single FST gene encodes two isoforms, FST317 and FST344 containing 317 and 344 amino acids respectively, resulting from alternative splicing of the precursor mRNA.
Follistatin is a secreted glycoprotein that was first identified as a folliclestimulating hormone inhibiting substance in ovarian follicular fluid.Human Follistatin cDNA encodes a 344 amino acid protein with a 29 aa signal sequence, an Nterminal atypical TGF binding domain, three Follistatin domains that contain EGF like and kazallike motifs, and a highly acidic Cterminal tail. Follistatin is a secreted protein that binds to ligands of the TGF-Beta family and regulates their activity by inhibiting their access to signaling receptors..
Follistatin 315 primary function is the binding and bioneutralization of members of the TGF-β superfamily, with a particular focus on activin, a paracrine hormone
Either by genetic elimination or by increasing the amount of follistatin, resulted in greatly increased muscle mass.In 2009, research with macaque monkeys demonstrated that regulating follistatin via gene therapy also resulted in muscle growth and increases in strength.A study has also shown that increased levels of follistatin, by leading to increased muscle mass of certain core muscular groups, can increase life expectancy in cases of spinal muscular atrophy in animal models.