Peripherin is a type III
Intermediate filament (IF) protein expressed mainly in neurons of the
peripheral nervous system (PNS). It is also found in neurons of the
central nervous system (CNS) that have projections toward peripheral structures, such as spinal motor neurons. Its size, structure, and sequence/location of protein motifs is similar to other type III IF proteins such as
desmin,
vimentin and
glial fibrillary acidic protein (GFAP). Like these proteins, peripherin can self-assemble to form homopolymeric filamentous networks (networks formed from peripherin
protein dimers), but it can also heteropolymerize with
neurofilaments in several neuronal types. This
protein in humans is encoded by the
PRPH gene. Peripherin is thought to play a role in neurite elongation during development and axonal regeneration after injury, but its exact function is unknown. It is also associated with some of the major neuropathologies that characterize
amyotropic lateral sclerosis (ALS), but despite extensive research into how neurofilaments and peripherin contribute to ALS, their role in this disease is still unidentified.