Required for normal myelination and for normal organization of the cytoplasm and the formation of Cajal bands in myelinating Schwann cells. Required for normal PRX location at appositions between the abaxonal surface of the myelin sheath and the Schwann cell plasma membrane. Possibly involved in membrane-cytoskeleton interactions of the central nervous system. Interacts with PRX; this enhances phosphorylation (PubMed:11430802). Identified in a dystroglycan complex that contains at least PRX, DRP2, UTRN, DMD and DAG1 (By similarity). Detected in Schwann cells at periaxonal myelin membranes. Detected in trigeminal nerve Schwann cells (PubMed:11430802). Detected in brain cortex and hippocampus. Detected in brain membrane fractions and highly enriched in the postsynaptic density (at protein level).