Neurofilaments are intermediate (10–12nm) filaments located specifically in neurons. There are three classes of neurofilaments: NF-L (68kD), NF-M (160kD), and NF-H (200kD). The neurofilaments are long helical proteins which polymerize to form a rigid cytoskeleton in the neuron. This polymerized network is composed of all three filaments, and the stoichiometry of association varies during development. Neurofilaments are posttranslationally modified both by phosphorylation and glycosylation. Like other intermediate filament proteins, phosphorylation likely mediates neurofilament dynamics. However, how O-linked N-acetylglucosamine residues function to modify neurofilament function remains unclear.