peripherin

Peripherin is a protein name used for two related but distinct proteins in humans: peripherin (PRPH) and peripherin-2 (PRPH2), sometimes referred to simply as peripherin in retina. Both belong to the family of intermediate filament proteins, but they are expressed in different tissues and have different cellular roles. Peripherin-2 is also known as retinal degeneration slow (RDS) protein.

Peripherin (PRPH) is a neuron-specific type III intermediate filament protein primarily expressed in the peripheral nervous system. It contributes to the cytoskeletal network that supports axons and dendrites, and it can form filaments in combination with other intermediate filament proteins such as neurofilament components. In peripheral neurons, peripherin participates in maintaining axonal caliber and may influence neurite outgrowth and resilience to injury. In many species, loss or alteration of PRPH affects long or highly branched axons, illustrating a role in axonal architecture rather than signaling.

Peripherin-2 (PRPH2), commonly referred to as peripherin in the retina, is a photoreceptor-specific outer segment membrane protein with a role in disc morphogenesis and outer segment maintenance. It localizes to the rims of photoreceptor outer segment discs and forms complexes with ROM1 to create the structural rim network essential for proper outer segment organization. Mutations in PRPH2 are associated with inherited retinal dystrophies, including retinitis pigmentosa and pattern or macular dystrophies, reflecting its critical function for photoreceptor integrity and function.

Together, peripherin and peripherin-2 illustrate how related proteins with the same name can have specialized, tissue-specific roles in neuronal structure and sensory function.