The Structure of the N-terminal Region of Murine Skeletal Muscle α-Dystroglycan Discloses a Modular Architecture

Dystroglycan (DG) is a cell surface receptor consisting of two subunits: α-dystroglycan, extracellular and highly glycosylated, and β-dystroglycan, spanning the cell membrane. It is a pivotal member of the dystrophin-glycoprotein complex and is involved in a wide variety of important cellular processes such as the stabilization of the muscle fiber sarcolemma or the clustering of acetylcholine receptors. We report the 2.3-à resolution crystal structure of the murine skeletal muscle N-terminal α-DG region, which confirms the presence of two autonomous domains; the first finally identified as an Ig-like and the second resembling ribosomal RNA-binding proteins. Solid-phase laminin binding assays show the occurrence of protein-protein type of interactions involving the Ig-like domain of α-DG.