Composition

• Amino Acid Chain: It is comprised of a sequence of 344 amino acids.

• Molecular Structure: It is a single-chain glycoprotein. Its structure is defined by an N-terminal domain followed by three “Follistatin domains” (FSD 1, 2, and 3).

• Precursor vs. Mature Form: The 344-amino acid chain is actually the precursor (pre-peptide). Once the signal peptide (the first 29 amino acids) is removed during secretion, it becomes the mature Follistatin-315 (FST-315) isoform.