FST Human, Sf9

Follistatin is encoded by the FST gene, which produces two main isoforms through alternative splicing: FST317 and FST344. These isoforms contain 317 and 344 amino acids, respectively . The protein consists of three cysteine-rich domains, each followed by a protease-inhibitory kazal domain .

The Human Recombinant Follistatin expressed in Sf9 cells (derived from the fall armyworm, Spodoptera frugiperda) is produced using a baculovirus expression system. This method allows for the production of a glycosylated polypeptide chain containing 295 amino acids (30-317 a.a.) with a molecular mass of 32.5 kDa . The recombinant protein is expressed with a 7-amino acid His tag at the C-terminus and purified using proprietary chromatographic techniques .

Follistatin is a multifunctional protein with several key roles:

• Inhibition of Activins: Follistatin was initially discovered as an activin antagonist. Activins are involved in the regulation of follicle-stimulating hormone (FSH) secretion from the pituitary gland. By binding to activins, follistatin prevents them from interacting with their receptors, thereby inhibiting their biological activity .
• Muscle Growth Regulation: Follistatin inhibits myostatin, a negative regulator of muscle growth. This inhibition promotes muscle hypertrophy and has potential therapeutic applications for muscle-wasting diseases .
• Bone Metabolism: Follistatin also interacts with bone morphogenetic proteins (BMPs), influencing bone formation and repair .

Recombinant follistatin has several research and therapeutic applications:

• Cell Culture: It is used in cell culture systems to study the effects of activin and myostatin inhibition .
• Therapeutic Potential: Due to its role in muscle growth regulation, follistatin is being investigated for potential treatments for conditions such as muscular dystrophy and other muscle-wasting disorders .

The recombinant follistatin protein is typically stored at -20°C for long-term storage. It is recommended to add a carrier protein (0.1% HSA or BSA) to prevent degradation during storage. Avoiding multiple freeze-thaw cycles is crucial to maintain protein stability .

In summary, Human Recombinant Follistatin (Sf9) is a valuable tool in both research and potential therapeutic applications due to its ability to modulate key biological processes. Its production in Sf9 cells ensures a high level of purity and functionality, making it an essential component in the study of TGF-β family proteins.