PRX (periaxin) is a scaffolding protein essential for peripheral nerve myelin maintenance and lens fiber cell function. PRX functions as part of dystroglycan complexes in Schwann cells and EZR/AHNAK-containing complexes in eye lens fiber cells, serving critical roles in myelin organization. The protein is required for normal transport of myelin basic protein (MBP) mRNA from the perinuclear to paranodal regions and facilitates remyelination following nerve injury. PRX enables proper Schwann cell elongation and internodal length regulation, which are critical for saltatory conduction of nerve impulses; shorter internodes result in slower nerve transmission. The protein recruits DRP2 to the Schwann cell plasma membrane and is essential for forming appositions between the myelin sheath's abaxial surface and the Schwann cell membrane, thereby restricting cytoplasm to specific regions. PRX also regulates formation of Cajal bands and Schmidt-Lanterman incisures—cytoplasm-filled regions on myelinated nerves. In the eye, PRX maintains normal protein composition of lens fiber cell plasma membranes and normal fiber cell morphology. Mutations in PRX cause demyelinating Charcot-Marie-Tooth disease type 4F and Dejerine-Sottas syndrome, highlighting its critical role in maintaining myelin structure and nerve function essential for normal sensory perception and motor control.