Dystroglycans are essential elements of the neuromuscular junction (NMJ). The gene for dystroglycan is expressed as a precursor protein that is post translationally cleaved into a 156 kDa extracellular peripheral membrane protein called alpha dystroglycan and a 43 kDa transmembrane protein, beta dystroglycan. The latter protein contains a PPxY motif that promotes binding to WW domain containing proteins, such as utrophin and dystrophin. Phosphorylation at tyrosine 892 within the PPxY motif may regulate c Src interactions with beta dystroglycan, as well as inhibit interactions with WW domain proteins. In skeletal muscle, beta dystroglycan is normally localized to the plasma membrane, however phosphorylation of Tyr892 leads to localization of beta dystroglycan to endosomal compartments along with c Src. Thus, phosphorylation at Tyr892 may have important roles in altering the localization of beta dystroglycan during NMJ formation.

Type I membrane protein.