Follistatin, an activin-binding protein, associates with heparan sulfate chains of proteoglycans on follicular granulosa cells.

Follistatin, an activin-binding protein secreted by cultured rat granulosa cells, was shown to associate with the cell surface by affinity labeling with 125I-activin. Addition of follistatin to the cultured cells demonstrated a typical ligand-binding saturation curve, suggesting that granulosa ce…