Deletion mutagenesis analysis has identified two regions in the betaglycan ectodomain of TGFBR3 that are capable of binding TGF‑β: the endoglin‑related region at the amino‑terminal region the the uromodulin‑related region at the carboxyl‑terminal region ,. Binding competition experiments indicate that TGFBR3 (uromoduline‑related region) binds inhibin and TGF‑β with the following relative affinities: TGF‑β2 > inhibin A > TGF‑β1. Current data (Esparza-Lopez et al., 2001) suggest that the betaglycan ectodomain contains two independent ligand binding domains that can perform specialized functions as co‑receptors of distinct members of the TGF‑β superfamily.