Is an adhesion molecule necessary for normal myelination in the peripheral nervous system. It mediates adhesion between adjacent myelin wraps and ultimately drives myelin compaction. Homodimer and homotetramer. Found only in peripheral nervous system Schwann cells. Expressed in the sciatic nerves at postnatal days P6 to P12. N-glycosylated; contains sulfate-substituted glycan. Belongs to the myelin P0 protein family.