Internexin, alpha-internexin, is a Class IV intermediate filament approximately 66 KDa. The protein was originally purified from rat optic nerve and spinal cord. The protein copurifies with other neurofilament subunits, as it was originally discovered, however in some mature neurons it can be the only neurofilament expressed. The protein is present in developing neuroblasts and in the Central Nervous System of adults. The protein is a major component of the intermediate filament network in small interneurons and cerebellar granule cells, where it is present in the parallel fibers.

Internexin, alpha-internexin, is a Class IV intermediate filament approximately 66 KDa. The protein was originally purified from rat optic nerve and spinal cord. The protein copurifies with other neurofilament subunits, as it was originally discovered, however in some mature neurons it can be the only neurofilament expressed. The protein is present in developing neuroblasts and in the Central Nervous System of adults. The protein is a major component of the intermediate filament network in small interneurons and cerebellar granule cells, where it is present in the parallel fibers.