Activin-Binding Protein from Rat Ovary Is Follistatin

TLDR

Activin, a TGF‑β family protein isolated from gonadal fluids, stimulates FSH release and has diverse cellular functions, yet its molecular binding partners remain unidentified. A rat ovarian activin‑binding protein was purified and found to be identical to follistatin, a specific inhibitor of FSH release, suggesting it mediates activin’s regulatory effects.

Abstract

Activin, a member of the transforming growth factor beta protein family, was originally isolated from gonadal fluids and stimulates the release of pituitary follicle-stimulating hormone (FSH). Activin has numerous functions in both normal and neoplastic cells. Various cells synthesize activin and have a specific binding site for this peptide. However, the molecular basis for its actions is unknown. A binding protein for activin was purified from rat ovary and was identical to follistatin, a specific inhibitor of FSH release. It is likely that the binding protein participates in the diverse regulatory actions of activin.