Page data last changed: . Registry refreshes and identity assessments are separate from scientific content review.
The circulating splice isoform of follistatin, distinct from the FS-288 form.
Also known as: FS-315 · FST-315
Part of the Growth hormone & IGF peptides cluster
Overview
Follistatin-315 (FS-315) is the longer of two follistatin isoforms generated by alternative splicing of the FST gene. Follistatin binds activin and related TGF-beta ligands, including myostatin. FS-315 is an investigational research protein, not authorized by Health Canada; this page is educational only.
Source & context
Biological / chemical source: Longer splice isoform of human follistatin (FST gene)
Primary research or clinical context: Investigational research protein; not authorized by Health Canada
Two isoforms
Alternative splicing of the FST transcript yields FS-288 and FS-315. FS-315 has an acidic C-terminal tail that lowers its affinity for cell-surface heparan sulfate, so it circulates more freely, whereas FS-288 binds tightly to cell surfaces. Both act by sequestering activin and related ligands.
Research interest and status
Because follistatin can bind myostatin, a negative regulator of muscle mass, it draws interest in muscle-biology research. Human data specific to administered follistatin proteins are limited. FS-315 is investigational, is not an approved drug in Canada, and this summary makes no therapeutic or performance claims.
Structure & chemistry
Molecular identity & reference confidence
Reference mass unavailable
Reference values are taken from the cited molecular record or curated profile. A database match is not independent laboratory verification; modifications, counter-ions, and formulations can change the measured mass.
- Molecular form
- Follistatin-315 (source record; form not independently established)
- Species
- Not established by this molecular identity audit
- Termini (N / C)
- Not specified / Not specified
Average reference mass
Reference policy updated: 2026-10-05
FAQ about Follistatin-315
What is Follistatin-315?+
Follistatin-315 (FS-315) is the longer of two follistatin isoforms generated by alternative splicing of the FST gene. Follistatin binds activin and related TGF-beta ligands, including myostatin. FS-315 is an investigational research protein, not authorized by Health Canada; this page is educational only.
What Canadian product status is recorded for Follistatin-315?+
Canadian product status for Follistatin-315 has not been verified in this profile. No verified record here does not mean no authorization exists. Status depends on the product, formulation and use; consult Health Canada's product records.
What is the typical length of Follistatin-315?+
Follistatin-315 is commonly described as approximately 315 amino acids (Activin-binding glycoprotein isoform).