Dystroglycan (also known as dystrophin-associated glycoprotein 1) is a member of the dystroglycan family that contains the WWW binding motif PPxY. This protein has alpha and beta subunits with approximate molecular weights of 156 kD and 43-50 kD, respectively. The dystroglycan beta subunit is an integral membrane protein, the alpha subunit is a ubiquitously expressed extracellular protein. Muscle and non-muscle isoforms differ by carbohydrate moieties (not protein sequence). Dystroglycan functions as an adhesion molecule responsible for interactions between extracellular matrix and the subsarcolemmal cytoskeleton. Dsytroglycan binds to lamin in the matrix and dystrophin in the cytoskeleton; phosphorylation regulates the association of interacting proteins. Dystroglycan binds to utrophin when unphosphorylated; c-Src, Fyn, Csk, NCK, and SHC when phosphorylated. Dystroglycan interacts with dystrophin through the WW domain. The Poly6171 antibody recognizes human phosphorylated dystroglycan (Tyr893) and has been shown to be useful for Western blotting.