Follistatin (FST) is a secreted glycoprotein that was first identified as a follicle-stimulating hormone inhibiting substance in ovarian follicular fluid (1, 2). Human Follistatin cDNA encodes a 344 amino acid (aa) protein with a 29 aa signal sequence, an N-terminal atypical TGF binding domain, three Follistatin domains that contain EGF-like and kazal-like motifs, and a highly acidic C-terminal 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. It was originally discovered as activin antagonists whose activity suppresses expression and secretion of the pituitary hormone FSH (follicle stimulating hormone). In addition to being a natural antagonist, follistatin can inhibit the activity of other TGF-Beta ligands including BMP-2,-4,-6,-7, Myostatin, GDF-11, and TGF-Beta1. Follistatin is expressed in the pituitary, ovaries, decidual cells of the endometrium, and in some other tissues. Recombinant human Follistatin is a 37.8 kDa protein containing 344 amino acids.
Follistatin is fascinating protein that can increase muscle mass beyond natural potential by suppressing myostatin. Scientists first identified follistatin while examining porcine (re: pig) follicular fluid in the ovaries.
Follistatin, specifically Follistatin 344 (FS344), quickly gained popularity in the bodybuilding community as a potential supplement to rapidly increase lean tissue mass. Another protein, follistatin-related gene (FLRG) acts on similar pathways as FS344 regarding its muscle building properties. Increased lean tissue mass could give a bodybuilder an advantage in a competitive setting and be the differentiating factor between first and second place.
1 . Follistatin-344 significantly increases the muscle mass and strength (by blocking the action of myostatin) - supports hyperplasia (new muscle cells), and active hypertrophy (enlargement of muscle cells).
2 . Follistatin-344 has potent anabolic effects (without concomitant androgenic activity), use Follistatin-344 leads to muscle hyperplasia (growth of new muscle fibers) and active hypertrophy (increasing the volume of existing muscle fibers)
3 . Follistatin-344 has the ability to maintain a strong athletes as massive as in muscle, although longer sport