Specialized Research

Follistatin-344

Also known as: FS-344, FST-344

Molecular Identifiers

Molecular Weight

~38 kDa

Overview

Recombinant 344-amino acid protein that functions as a potent myostatin and activin inhibitor. Binds to myostatin preventing its catabolic action on muscle tissue, promoting hypertrophy.

Clinical interest in Follistatin-344 lies in combined inhibition of myostatin and activins A and B, with potential for muscle hypertrophy, fibrosis reduction, and effects on the reproductive axis via FSH regulation. The broader inhibition compared with Follistatin-315 brings more potency on muscle mass but also greater hormonal impact. Human evidence in healthy subjects is limited, coming mostly from preclinical studies and trials in muscle diseases.

There is no regulatory approval for Follistatin-344 by any agency. It is marketed as a recombinant research protein and, in parts of the market, dispensed by compounding pharmacies as off-label use in mass-gain protocols, in short subcutaneous cycles of 10–30 days given its ~1.5-hour half-life and high cost. Myostatin inhibitors are banned by WADA at all times.

In direct comparison with Follistatin-315, the 344 isoform is the "full-length" form, longer, with greater heparan sulfate affinity and tissue binding — which translates into combined inhibition of myostatin and activins A/B. It results in greater potency on muscle mass at the price of more impact on FSH and the reproductive axis, in contrast with the more "muscle-only" profile of Follistatin-315. Regulatory status (no approval) and WADA prohibition are identical between the two isoforms.

Sequence (1 letter): MVRARHQPGGLCLLLLLLCQFMEDRSAQAGNCWLRQAKNGRCQVLYKTELSKEECCSTGRLSTSWTEEDVNDNTLFKWMIFNGGAPNCIPCKETCENVDCGPGKKCRMNKKNKPRCVCAPDCSNITWKGPVCGLDGKTYRNECALLKARCKEQPELEVQYQGRCKKTCRDVFCPGSSTCVVDQTNNAYCVTCNRICPEPASSEQYLCGNDGVTYSSACHLRKATCLLGRSIGLAYEGKCIKAKSCEDIQCTGGKKCLWDFKVGRGRCSLCDELCPDSKSDEPVCASDNATYASECAMKEAACSSGVLLEVKHSGSCNSISEDTEEEEEDEDQDYSFPISSILEW

Protein of 344 amino acids. Full sequence too long for display.

Half-life

~1.5 hours

Administration Route

Subcutaneous

Category

Specialized Research

Mechanism of Action

  • Myostatin inhibition via direct binding
  • Activin A and B blockade
  • Promotion of muscle growth via disinhibition of anabolic pathways
  • Reduction of tissue fibrosis
  • Role in FSH (follicle-stimulating hormone) regulation

Dosage Protocol

Data compiled from the literature. This does not constitute medical advice.

Parameter Value
Dose 100-200 mcg per injection
Frequency Once daily
Timing Morning or post-workout
Duration 10-30 days

Reported Side Effects

Adverse effects described in the literature. Severity and frequency vary between individuals.

  • Injection site redness
  • Fatigue
  • Headache
  • Joint discomfort

Product Properties

Purity >97%
Appearance White lyophilized powder
Solubility Soluble in water and bacteriostatic water. Reconstitute gently — do not vortex.
Source Recombinant DNA technology (E. coli or HEK293 cells)
Storage Lyophilized: -20°C for up to 2 years, 2-8°C for up to 6 months. Reconstituted: 2-8°C for up to 2 weeks. Protect from light and moisture. Avoid repeated freeze-thaw cycles. Aliquot for long-term storage.

Presentations & Preparation

Vials of Follistatin-344 found in the research market:

1 mg

Reconstitution

  • Diluent: Bacteriostatic water
  • Volume: 1 ml per 1 mg vial
  • Inject diluent slowly
  • Gently swirl without shaking
  • Immediate use after reconstitution recommended

Storage

  • Lyophilized: Frozen -20°C (long-term)
  • Reconstituted: Refrigerated 2-8°C (up to 7 days)
  • Delicate protein — avoid freeze/thaw cycles
  • Protect from light
Reconstitution Calculator

Scientific Studies

Published studies on Follistatin-344.

2015 · Molecular Therapy

A phase 1/2a follistatin gene therapy trial for becker muscular dystrophy

Mendell JR, Sahenk Z, Malik V, Gomez AM, Flanigan KM, Lowes LP, Alfano LN, Berry K, Meadows E, Lewis S, Braun L, Shontz K, Rouhana M, Clark KR, Rosales XQ, Al-Zaidy S, Govoni A, Rodino-Klapac LR, Hogan MJ, Kaspar BK

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