Several agrin (AGRN) ligands require the presence of heparan-sulfate GAG sidechains and probably represent interactions with them. Extracellular ligands include Beta-amyloid (Donahue et al. 1999, Cotman et al. 2000). Other ligands (unconfirmed in humans) include alpha-synuclein fibrils (chicken - Liu et al. 2005), HB-GAM/pleiotropin (Dagget et al. 1996), thrombospondin and FGF2 (Cotman et al. 1999).