Dlg5 interacts with the TGF-ß receptor and promotes its degradation.

Discs large homolog 5 (Dlg5) is a member of the membrane-associated guanylate kinase adaptor family of proteins and is involved in epithelial-to-mesenchymal transition via transforming growth factor-ß (TGF-ß) signaling. However, the mechanism underlying the regulation of TGF-ß signaling is unclear. We show here that Dlg5 interacts and colocalizes with both TGF-ß type I (TßRI) and type II (TßRII) receptors at the plasma membrane. TßRI activation is not required for this interaction. Furthermore, the overexpression of Dlg5 enhances the degradation of TßRI. Proteasome inhibitors inhibited this enhanced degradation. These results suggest that Dlg5 interacts with TßRs and promotes their degradation.